All lectures take place in Biosciences Complex Room 1101
Day 0 (Sun): Conference Welcoming
July 15
July 15
16:00-18:00
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Reception at the Agnes Etherington Gallery
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18:00-19:30
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Dinner at Leonard Hall for Smith House residents
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Day 1 (Mon)
July 16
July 16
7:30-8:30
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Breakfast at Leonard Hall for Smith House residents
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8:45-9:00
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Welcoming words: S. Courteau (Conference chair)
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S1 : What do Scaling Relations tell us about Dark Matter and Galaxy Formation?
Chair : Sandra Faber
9:00-10:00
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Setting the Stage. Panel with:
Rachel Bezanson (Pittsburgh) [15] Andrea Macciò (NYUAD) [15] Rachel Somerville (CCA) [15] + 15 minutes of discussion |
10:10-10:35
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Sandra Faber (UCSC) [20+5]
The importance of galaxy evolution in understanding scaling laws |
10:35-11:00
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Coffee break / posters in Biosciences Atrium
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S2 : Star Formation and the Galaxy Main Sequence
Chair : Jim Stone
11:00-11:25
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Robert Kennicutt [20+5]
A review of Cambridge festschrift |
11:35-noon
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Daniella Calzetti (UMASS) [20+5] Spatially-resolved star formation |
noon-14:00
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Lunch at Leonard Hall
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Chair : Alar Toomre
14:00-14:25
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Linda Tacconi (MPE) [20+5] The physics of star formation and the galaxy main sequence |
14:25-14:50
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Andrey Kravtsov (Chicago) [20+5] How galaxies form stars: the physical origin of long gas depletion time and Kennicutt-Schmidt relation |
14:50-15:15
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Andi Burkert (LMU) [20+5] A bathtub model for the star-forming interstellar medium |
15:15-15:45
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Coffee break / posters in Biosciences Atrium
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Chair : David Hanes
15:45-16:05
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Steve Eales (Cardiff) [15+5] The New Galaxy-Evolution Paradigm Emerging from the Herschel Surveys |
16:05-16:25
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Tjitske Starkenburg (Flatiron) [15+5] The populations of star forming and quenched galaxies |
16:30-16:45
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Flash Talks [4 speakers x 3 mins each]
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Chair : Stéphane Courteau
17:00-18:30
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Panel discussion on the Birth of the Cold Dark Matter Theory
Panelists: Dick Bond, Ken Freeman, Jim Peebles, Joel Primack, Michael Turner [15 mins each] |
20:00-22:00
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Dinner at Tir Nan Og Irish Pub
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Day 2 (Tue)
July 17
July 17
7:30-8:30
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Breakfast at Leonard Hall for Smith House residents
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S3: Generalized Scaling Relations of Galaxies
Chair : Kristine Spekkens
Chair : Kristine Spekkens
9:00-9:25
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Aaron Dutton (NYUAD) [20+5] Why do size-mass-velocity relations exist? |
9:25-9:50
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Danail Obreschkow (Perth) [20+5] A modern view on the scale dependence of galaxies |
9:50-10:10
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Julio Navarro (UVic) [15+5] Cold dark matter self-similarity and galaxy scaling laws |
10:10-10:30
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Coral Wheeler (Caltech) [15+5] The RAR is a natural consequence of the TFR |
10:30-11:00
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Coffee Break / posters in Biosciences Atrium
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Chair : Roger Davies
11:00-11:20
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Nathalie Ouellette (Queen's/CPARC) [15+5] Scaling relations and bimodalities in the Virgo cluster |
11:20-11:40
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John Forbes (Harvard) [15+5] A guide to the parameters controlling disk galaxy observables |
11:40-noon
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Paul Schechter (MIT) [15+5] The fundamental line for dark matter haloes and the stellar mass fundamental plane for elliptical galaxies |
noon-14:00
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Lunch at Leonard Hall
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Chair : Karl Gebhardt
14:00-14:25
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14:30-14:55
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Michele Cappellari (Oxford) [20+5] Generalized structural scaling relations of galaxies |
14:55-15:20
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Pieter van Dokkum (Yale) [20+5] A galaxy lacking dark matter? |
15:20-15:50
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Coffee Break / posters in Biosciences Atrium
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Chair : Nathalie Ouellette
15:50-16:10
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Dan Taranu (Princeton) [15+5] Disk galaxy scaling relations in the LSST/SKA era |
16:10-16:30
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Gerhardt Meurer (Perth) [15+5] Galaxy clocks and other star forming disk galaxy scaling relations |
16:30-16:45
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Flash Talks [5 speakers x 3 mins each]
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18:30-23:00
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Gala Banquet at the Isabel Bader Centre (150 pax)
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Day 3 (Wed)
July 18
July 18
7:30-8:30
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Breakfast at Leonard Hall for Smith House residents
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S4: Constraints on the Nature of Dark Matter from Sky Surveys and Astroparticle Searches
Chair : Michael Strauss
Chair : Michael Strauss
9:00-9:25
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Jim Gunn (Princeton) [20+5] My life as an instrumentalist (featuring SDSS & PFS) |
9:25-9:50
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Karl Gebhardt (Texas) [20+5] HETDEX |
9:50-10:10
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Matthew Colless (ANU) [15+5] Taipan: a massive redshift and peculiar velocity survey to study dark matter and gravity in the local universe |
10:10-10:30
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Sarah Schon (Queen's) [15+5] Constraining the nature of dark matter using the first galaxies |
10:30-11:00
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Coffee Break / posters in Biosciences Atrium
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Chair : Aaron Vincent
11:00-11:25
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Ken Clark (Queen's/CPARC) [20+5] Summary of direct detection experiments |
11:25-11:45
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Peter Quinn (ICRAR) [15+5] A radio astronomy search for axion dark matter |
noon-13:00
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Panel discussion on The future of dark matter detections
with Graciela Gelmini (UCLA), Katie Mack (NCSU), Tony Noble (CPARC Director), Maxim Pospelov (Perimeter Institute) |
13:00
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Lunch in town
Open afternoon. Explore Kingston! |
15:30
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Tour McDonald Institute Visitor Centre (optional) w/ Nathalie Ouellette
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18:00-21:00
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Dinner Cruise: Thousand Islands Cruise from Kingston's Crawford Wharf
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Day 4 (Thu)
July 19
July 19
7:30-8:30
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Breakfast at Leonard Hall for Smith House residents
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S5: Local and Global Processes
Chair : Rachel Somerville
Chair : Rachel Somerville
8:45-9:10
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Alexie Leauthaud (UCSC) [20+5] Impact of halo mass on scaling relations |
9:15-9:40
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Avishai Dekel ft. Jonathan Freundlich (Hebrew Univ.) [20+5] The Magic Scale of Galaxies and the KS Relation from Supernova Feedback |
9:40-10:05
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Romeel Davé (Edinburgh) [20+5] Galaxy-Black Hole Scaling Relations in the Simba Galaxy Formation Simulations |
10:05-10:25
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Bruno Henriques (ETH) [15+5] The evolution of black-hole properties and the implications for galaxy quenching |
10:25-10:55
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Coffee break / posters in Biosciences Atrium
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Chair : Preethi Nair
11:00-11:25
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Vardha Bennert (CalPoly) [20+5] Calibrating the Black Hole Mass Scaling Relations |
11:25-11:45
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Sabine Thater (AIP/Leibniz) [15+5] Revisiting the black hole - galaxy scaling relations with the SMASHING sample |
11:45-12:05
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Marvin Blank (NYUAD) [15+5] Scaling relations in the NIHAO project with AGN feedback |
12:10-14:00
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Lunch at Leonard Hall
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S6 : Dependence of Scaling Relations on Environment and Cosmic Time
Chair : Matthew Colless
14:00-14:25
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Reinhard Genzel (MPE) [20+5] Galactic dynamics, feedback and dark matter at z~0.7-2.7 |
14:25-14:50
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Arjen van der Wel (MPIA) [20+5] Evolution of dynamical scaling relations to z=1 LEGA-C |
14:50-15:10
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15:10-15:30
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Debora Pelliccia (UCD) [15+5] Does Time and Environment affect the Stellar-Mass Tully-Fisher Relation? |
15:30-16:00
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Coffee Break in Biosciences Atrium (Poster boards must be taken down)
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Chair : Marc Verheijen
16:00-16:25
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Brent Tully (UH) [20+5] The Faint End of the Group Mass Function |
16:25-16:45
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Caroline Straatman (MPIA) [15+5] The stellar mass Tully-Fisher relation from gas and stars since z~1. |
16:45-17:05
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John Moustakas (Siena College) [15+5] The Efficiency of Star Formation and the SHMR in Massive Dark Matter Halo |
17:05-17:25
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Ulrike Kuchner (Nottingham) [15+5] The impact of “pre-processing” on the galaxy mass-size scaling relation |
17:25-17:40
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Flash Talks [5 speakers x 3 mins each]
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18:00
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Dinner downtown
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18:30
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Reception for Public Lecture on The Dark Side of the Universe
by Michael S. Turner, Rauner Distinguished Service Professor and Director of the Kavli Institute for Cosmological Physics at The University of Chicago Biosciences Atrium MC: Larry Widrow |
19:30-20:30
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Public Lecture on The Dark Side of the Universe
Biosciences Auditorium |
Day 5 (Fri)
July 20
July 20
7:30-8:30
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Breakfast at Leonard Hall for Smith House residents
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S6 / Cont. : Dependence of Scaling Relations on Environment and Cosmic Time
Chair : Rachel Bezanson
Chair : Rachel Bezanson
9:00-9:15
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Flash Talks [5 speakers x 3 mins each]
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9:25-9:45
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Henk Hoekstra (Leiden) [15+5] Scaling relations from weak lensing |
9:50-10:15
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Mike Hudson (Waterloo) [15+5] Extending galaxy scaling relations to include the dark matter halo using weak gravitational lensing |
10:15-10:35
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Tucker Jones (UCD) [15+5] Scaling relations and feedback at low masses and early cosmic times |
10:35-11:00
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Coffee break in Biosciences Atrium
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11:00-11:25
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Annalisa Pillepich (MPIA) [15+5] The distribution of luminous and dark matter within galaxies: Insights from the IllustrisTNG simulations |
11:25-11:45
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Sarah Wellons (Northwestern) [15+5] Contextualizing the time evolution of galaxy scaling relations with large-volume cosmological simulations |
12:00-14:00
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Lunch at Leonard Hall
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S7 : Alternatives to (Cold) Dark Matter?
Chair : Andrea Macciò
14:00-14:25
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14:25-14:50
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Louis Strigari (Texas Tech) [20+5] Can dwarf galaxies discriminate cold dark matter and alternatives? |
14:50-15:15
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Carlos Frenk (Durham) [20+5] A conclusive test of cold dark matter |
15:15-15:20
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Poster Awards
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15:20-15:45
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Coffee break in Biosciences Atrium
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Chair : Joe Bramante
15:45-16:10
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Benoît Famaey (Strasbourg) [20+5] The Mass Discrepancy-Acceleration Relation: Feedback, modified gravity, or baryon-dark matter interactions? |
16:10-16:30
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Sean Tulin (York) [15+5] Self-interacting dark matter and small scale structure |
16:30-16:50
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Mark Lovell (Iceland) [15+5] Dark matter models with a power spectrum cutoff: Then and now |
16:50-17:10
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Benjamin Moster (LMU) [15+5] Galaxy scaling relations for WDM models based on the empirical model Emerge |
17:10-17:30
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General Discussion
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17:30-18:00
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Guests of Honour closing words
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18:15-21:00
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Closing reception in Biosciences Atrium
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Day 6 (Sat)
July 21
July 21
7:30-8:30
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Breakfast at Leonard Hall for Smith House residents
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Attendants depart after breakfast.
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Spatially-resolved star formation
The galaxy-wide relation between star formation and gas is well established, but its `local' counterpart is still a subject of controversy. I will present recent results by several authors, discussing both the pros and cons of different approaches to the derivation of local star formation rates. While gas measurements are by necessity almost always instantaneous and local, the conversion of light to star formation rates needs to account for the dispersal of stars after birth. Discrepancies in the results published in the literature can often be explained in light of this physical difference.
For a copy of the presentation, please click here
The galaxy-wide relation between star formation and gas is well established, but its `local' counterpart is still a subject of controversy. I will present recent results by several authors, discussing both the pros and cons of different approaches to the derivation of local star formation rates. While gas measurements are by necessity almost always instantaneous and local, the conversion of light to star formation rates needs to account for the dispersal of stars after birth. Discrepancies in the results published in the literature can often be explained in light of this physical difference.
For a copy of the presentation, please click here
The physics of star formation and the galaxy main sequence
I will review our knowledge of star formation scaling relations over cosmic time. I will draw on results from the recent surveys of molecular gas (mostly through CO) and dust, from Herschel, ALMA and NOEMA and place them in the context of the star formation main-sequence.
For a copy of the presentation, please click here
I will review our knowledge of star formation scaling relations over cosmic time. I will draw on results from the recent surveys of molecular gas (mostly through CO) and dust, from Herschel, ALMA and NOEMA and place them in the context of the star formation main-sequence.
For a copy of the presentation, please click here
How galaxies form stars: the physical origin of long gas depletion time and Kennicutt-Schmidt relation
Formation of stars in galaxies is a complex multi-scale process. Despite this complexity, the star formation rate (SFR) on kiloparsec- and larger scales exhibits a rather tight Kennicutt-Schmidt relation (KSR). The long value of the gas depletion time - the inverse of the KSR normalization - was a long standing puzzle, because it is much longer than time scales of any relevant processes in the ISM. Many galaxy formation simulations could reproduce the observed depletion time and KSR, but the physics controlling them was not well understood. Moreover, recent simulations with strong stellar feedback showed that depletion time was nearly insensitive to the local efficiency of star formation - a phenomenon described as "self-regulation." I will present results of a suite of galaxy simulations that systematically explore this behavior and a physical model that explains the physics behind both the observed long gas depletion times in galaxies and results of recent numerical simulations.
For a copy of the presentation, please click here
Formation of stars in galaxies is a complex multi-scale process. Despite this complexity, the star formation rate (SFR) on kiloparsec- and larger scales exhibits a rather tight Kennicutt-Schmidt relation (KSR). The long value of the gas depletion time - the inverse of the KSR normalization - was a long standing puzzle, because it is much longer than time scales of any relevant processes in the ISM. Many galaxy formation simulations could reproduce the observed depletion time and KSR, but the physics controlling them was not well understood. Moreover, recent simulations with strong stellar feedback showed that depletion time was nearly insensitive to the local efficiency of star formation - a phenomenon described as "self-regulation." I will present results of a suite of galaxy simulations that systematically explore this behavior and a physical model that explains the physics behind both the observed long gas depletion times in galaxies and results of recent numerical simulations.
For a copy of the presentation, please click here
A bathtub model for the star-forming interstellar medium
The bathtub model of the star forming interstellar medium (ISM) is based on the powerful constraint that mass has to be conserved when gas flows through it's various thermal and density phases, ending up eventually in a young star or being blown away by stellar feedback. It predicts that the star formation rate of a molecular cloud is not determined by the cloud's mass or its internal collapse timescale, but rather by the accretion rate of new gas. For the most simple case of a constant accretion flow an equilibrium state is reached quickly where the star formation rate equals the accretion rate and where the dense gas mass is constant and independent of time. The mass of the young star cluster, on the other hand, increases linearly with time. The stellar mass fraction therefore represents a sensitive clock to measure the age of the star-forming region. The bathtub models predicts that the efficiency of star formation is small, of order 1\%, even in the dense filamentary phases of molecular clouds. It provides a simple explanation for the dense gas fraction of order 10\% in molecular clouds and for the large gas depletion timescales of star-forming galaxies of order $5 \times 10^8 - 10^9$ yrs.
For a copy of the presentation, please click here
The bathtub model of the star forming interstellar medium (ISM) is based on the powerful constraint that mass has to be conserved when gas flows through it's various thermal and density phases, ending up eventually in a young star or being blown away by stellar feedback. It predicts that the star formation rate of a molecular cloud is not determined by the cloud's mass or its internal collapse timescale, but rather by the accretion rate of new gas. For the most simple case of a constant accretion flow an equilibrium state is reached quickly where the star formation rate equals the accretion rate and where the dense gas mass is constant and independent of time. The mass of the young star cluster, on the other hand, increases linearly with time. The stellar mass fraction therefore represents a sensitive clock to measure the age of the star-forming region. The bathtub models predicts that the efficiency of star formation is small, of order 1\%, even in the dense filamentary phases of molecular clouds. It provides a simple explanation for the dense gas fraction of order 10\% in molecular clouds and for the large gas depletion timescales of star-forming galaxies of order $5 \times 10^8 - 10^9$ yrs.
For a copy of the presentation, please click here
The New Galaxy-Evolution Paradigm Emerging from the Herschel Surveys
This conference is largely based on many decades of optical surveys. However, the submillimetre surveys with the Herschel Space Observatory have revealed a different picture of the galaxy population, which presents a major challenge for our understanding of galaxy evolution. Instead of galaxies being divided into a star-forming ‘main sequence’ and a separate class of ‘passive galaxies’, which requires a strong quenching process to move galaxies from one class to the other, the Herschel surveys show that galaxies lie on a single Galaxy Sequence, with morphology and star-formation efficiency gradually changing along it. The Herschel surveys also reveal rapid galaxy evolution at very low redshift, which is difficult to explain because dark-matter halos are growing very slowly at low redshifts. I will describe these recent results, many of which have only emerged in the last year, and their radical implications. I will present a heuristic model that can explain both the new and existing results. In this model, the gas supply to galaxies is stochastically cut off, with the strong low-redshift evolution and the curvature in the Galaxy Sequence being produced by the gradual cosumption of the remaining gas.
For a copy of the presentation, please click here
This conference is largely based on many decades of optical surveys. However, the submillimetre surveys with the Herschel Space Observatory have revealed a different picture of the galaxy population, which presents a major challenge for our understanding of galaxy evolution. Instead of galaxies being divided into a star-forming ‘main sequence’ and a separate class of ‘passive galaxies’, which requires a strong quenching process to move galaxies from one class to the other, the Herschel surveys show that galaxies lie on a single Galaxy Sequence, with morphology and star-formation efficiency gradually changing along it. The Herschel surveys also reveal rapid galaxy evolution at very low redshift, which is difficult to explain because dark-matter halos are growing very slowly at low redshifts. I will describe these recent results, many of which have only emerged in the last year, and their radical implications. I will present a heuristic model that can explain both the new and existing results. In this model, the gas supply to galaxies is stochastically cut off, with the strong low-redshift evolution and the curvature in the Galaxy Sequence being produced by the gradual cosumption of the remaining gas.
For a copy of the presentation, please click here
The populations of star forming and quenched galaxies
Galaxies having little to no active star formation are termed "quenched" but the definition of "quenched" varies widely through the literature. Moreover, the galaxy star formation main sequence itself varies depending on the dataset and the star formation rate indicators used. We explore the populations of star forming and quenched galaxies in a large observational dataset plus numerous independent sets of simulated galaxies from large-scale and zoom cosmological simulations. Moreover, we build mock galaxy spectra for all simulated galaxies and compare the mock observed star formation rate and quenching indicators to the properties in the simulations and to the star formation and quenching indicators of observed galaxies. We discuss the galaxy main sequence and quenched isolated galaxy populations in theoretical predictions, mock observations, and observational data, how to define “quenched” in a consistent way, and the implications of this comparison on the star formation and feedback processes in galaxies.
For a copy of the presentation, please click here
Galaxies having little to no active star formation are termed "quenched" but the definition of "quenched" varies widely through the literature. Moreover, the galaxy star formation main sequence itself varies depending on the dataset and the star formation rate indicators used. We explore the populations of star forming and quenched galaxies in a large observational dataset plus numerous independent sets of simulated galaxies from large-scale and zoom cosmological simulations. Moreover, we build mock galaxy spectra for all simulated galaxies and compare the mock observed star formation rate and quenching indicators to the properties in the simulations and to the star formation and quenching indicators of observed galaxies. We discuss the galaxy main sequence and quenched isolated galaxy populations in theoretical predictions, mock observations, and observational data, how to define “quenched” in a consistent way, and the implications of this comparison on the star formation and feedback processes in galaxies.
For a copy of the presentation, please click here
Why do size-mass-velocity relations exist?
Galaxies exist with a wide range of masses, sizes and velocities, yet these properties obey a number of scaling relations (e.g., Tully-Fisher, Faber-Jackson, Fundamental Plane). The small scatter in these relations hints at an underlying simplicity in the seemingly complex process of galaxy formation. In this review I will discuss the impact of different mass, size and velocity definitions, including attempts to put all types of galaxies onto a common system. Using insights from semi analytic models and cosmological hydrodynamical simulations I will discuss the role of the underlying dark matter haloes vs internal baryonic processes in setting these relations.
For a copy of the presentation, please click here
Galaxies exist with a wide range of masses, sizes and velocities, yet these properties obey a number of scaling relations (e.g., Tully-Fisher, Faber-Jackson, Fundamental Plane). The small scatter in these relations hints at an underlying simplicity in the seemingly complex process of galaxy formation. In this review I will discuss the impact of different mass, size and velocity definitions, including attempts to put all types of galaxies onto a common system. Using insights from semi analytic models and cosmological hydrodynamical simulations I will discuss the role of the underlying dark matter haloes vs internal baryonic processes in setting these relations.
For a copy of the presentation, please click here
A Modern View on the Scale Dependence of Galaxies
The laws of mechanics – even relativistic ones – exhibit an implicit scale invariance, which leads us to expect that gravitationally evolved systems obey a set of universal scaling relations. Measurements of galaxy masses, sizes and kinematics roughly confirm these relations, but also expose significant intrinsic scatter and systematic deviations, breaking the scale invariance. Recent simulations and precision measurements of galactic angular momentum have opened a new chapter in the study of classical scaling relations, enabling us to connect their scatter and scale dependence to the randomness and weak scale dependence of the cosmic web, as well as to scale dependent baryonic physics in galactic disks. This talk will review the meaning of scale invariance in galaxies, discuss modern advances and propose a synthetic scheme of two- and three-dimensional scaling laws, which can collectively account for the systematic scale dependence seen in galaxies.
For a copy of the presentation, please click here
The laws of mechanics – even relativistic ones – exhibit an implicit scale invariance, which leads us to expect that gravitationally evolved systems obey a set of universal scaling relations. Measurements of galaxy masses, sizes and kinematics roughly confirm these relations, but also expose significant intrinsic scatter and systematic deviations, breaking the scale invariance. Recent simulations and precision measurements of galactic angular momentum have opened a new chapter in the study of classical scaling relations, enabling us to connect their scatter and scale dependence to the randomness and weak scale dependence of the cosmic web, as well as to scale dependent baryonic physics in galactic disks. This talk will review the meaning of scale invariance in galaxies, discuss modern advances and propose a synthetic scheme of two- and three-dimensional scaling laws, which can collectively account for the systematic scale dependence seen in galaxies.
For a copy of the presentation, please click here
Cold dark matter self-similarity and galaxy scaling laws
I will discuss the origin of a number of well-established galaxy scaling relations, such as the Tully-Fisher relation and the mass discrepancy-radial acceleration relation, in a cold dark matter-dominated Universe. These relations arise from the self-similar structure of CDM halos, together with the mass-dependent regulation of galaxy formation that results from energetic feedback from evolving stars and supermassive black holes.
For a copy of the presentation, please click here
I will discuss the origin of a number of well-established galaxy scaling relations, such as the Tully-Fisher relation and the mass discrepancy-radial acceleration relation, in a cold dark matter-dominated Universe. These relations arise from the self-similar structure of CDM halos, together with the mass-dependent regulation of galaxy formation that results from energetic feedback from evolving stars and supermassive black holes.
For a copy of the presentation, please click here
The radial acceleration relation is a natural consequence of the baryonic Tully-Fisher relation
Galaxies covering several orders of magnitude in M* have been shown to follow the “Radial Acceleration Relation” (RAR), a relationship between gobs, the observed circular acceleration of the galaxy, and gbar, the acceleration due to the total galactic baryonic mass. I will show that the RAR slope, scatter and the acceleration scale are all natural consequences of the well known baryonic Tully-Fisher relation (BTFR), and further demonstrate that galaxies with a variety of baryonic and dark matter (DM) profiles and a wide range of dark halo and galaxy properties (well beyond those expected in CDM) lie on the RAR simply by requiring that their rotation curves satisfy the BTFR. I will also explore conditions needed to break this degeneracy: sub-kpc resolved rotation curves inside of “cored” DM-dominated profiles and/or outside 100 kpc could lie on BTFR but deviate in the RAR, providing new constraints on DM.
For a copy of the presentation, please click here
Galaxies covering several orders of magnitude in M* have been shown to follow the “Radial Acceleration Relation” (RAR), a relationship between gobs, the observed circular acceleration of the galaxy, and gbar, the acceleration due to the total galactic baryonic mass. I will show that the RAR slope, scatter and the acceleration scale are all natural consequences of the well known baryonic Tully-Fisher relation (BTFR), and further demonstrate that galaxies with a variety of baryonic and dark matter (DM) profiles and a wide range of dark halo and galaxy properties (well beyond those expected in CDM) lie on the RAR simply by requiring that their rotation curves satisfy the BTFR. I will also explore conditions needed to break this degeneracy: sub-kpc resolved rotation curves inside of “cored” DM-dominated profiles and/or outside 100 kpc could lie on BTFR but deviate in the RAR, providing new constraints on DM.
For a copy of the presentation, please click here
Scaling Relations and Bimodalities in the Virgo Cluster
The Spectroscopy and H-band Imaging of Virgo cluster galaxies (SHIVir) survey includes photometric, spectroscopic, and kinematic data for 190 Virgo cluster galaxies from which parameter distributions and fundamental scaling relations have been constructed. The distributions of both surface brightness and galaxy velocities is found to be bimodal about Vcirc ~ 125 km/s, hinting at the existence of dynamically unstable modes in the inner regions of galaxies. We find the slope and zero-point of the Virgo Tully-Fisher relation (TFR) match those of field galaxies, while scatter differences likely reflect distinct evolutionary histories. While TFR residuals remain independent of any galaxy parameters, Fundamental Plane residuals correlate strongly with the dynamical-to-stellar mass ratio, yielding stringent galaxy formation constraints. Stellar-to-total mass relations are also constructed for LTGs and ETGs revealing linear but distinct trends. This suite of results hints at processes in galaxy evolution in cluster environments that are not yet fully understood.
For a copy of the presentation, please click here
The Spectroscopy and H-band Imaging of Virgo cluster galaxies (SHIVir) survey includes photometric, spectroscopic, and kinematic data for 190 Virgo cluster galaxies from which parameter distributions and fundamental scaling relations have been constructed. The distributions of both surface brightness and galaxy velocities is found to be bimodal about Vcirc ~ 125 km/s, hinting at the existence of dynamically unstable modes in the inner regions of galaxies. We find the slope and zero-point of the Virgo Tully-Fisher relation (TFR) match those of field galaxies, while scatter differences likely reflect distinct evolutionary histories. While TFR residuals remain independent of any galaxy parameters, Fundamental Plane residuals correlate strongly with the dynamical-to-stellar mass ratio, yielding stringent galaxy formation constraints. Stellar-to-total mass relations are also constructed for LTGs and ETGs revealing linear but distinct trends. This suite of results hints at processes in galaxy evolution in cluster environments that are not yet fully understood.
For a copy of the presentation, please click here
A Guide to the Parameters Controlling Disk Galaxy Observables
Disk galaxies follow a wide array of simple scaling relations, yet the physics governing their evolution is non-linear and poorly constrained. I will present sophisticated but flexible models of the radially-resolved evolution of disk galaxies from z=4 to z=0. I will show how, using a machine learning approach, these models have been constrained to simultaneously fit a dozen galaxy scaling relations, some of which extend out to z=3. This approach also naturally identifies the most important parameters controlling each observable. This analysis provides a guide for which observations are most closely related to which physical parameters, and the common origin of the 1st and 2nd order galaxy scaling relations, along with the practical ability to generate thousands of radially-resolved model galaxies consistent with current data.
For a copy of the presentation, please click here
Disk galaxies follow a wide array of simple scaling relations, yet the physics governing their evolution is non-linear and poorly constrained. I will present sophisticated but flexible models of the radially-resolved evolution of disk galaxies from z=4 to z=0. I will show how, using a machine learning approach, these models have been constrained to simultaneously fit a dozen galaxy scaling relations, some of which extend out to z=3. This approach also naturally identifies the most important parameters controlling each observable. This analysis provides a guide for which observations are most closely related to which physical parameters, and the common origin of the 1st and 2nd order galaxy scaling relations, along with the practical ability to generate thousands of radially-resolved model galaxies consistent with current data.
For a copy of the presentation, please click here
The fundamental line for dark matter haloes and the stellar mass fundamental plane for elliptical galaxies
The effective radii, velocity dispersions and surface mass densities for galaxy halos lie along a line (or at most a ribbon, and certainly not a plane) in a 3 dimensional space. The same quantities, measured for the stars in elliptical galaxies, echo the parent halo quantities but fan out into a plane (probably with a small but finite thickness). The stellar quantities are affected by at least two dimensionless numbers -- call them efficiency and contraction -- that show both systematic variation with scale and stochastic variation at fixed scale. The virial theorem implies that stellar velocity dispersion is a good proxy for that of the parent halo (and hence its mass and radius), subject to caveats for low mass halos. Our argument elaborates on that of http://www.arxiv.org/pdf/1508.02358 .
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The effective radii, velocity dispersions and surface mass densities for galaxy halos lie along a line (or at most a ribbon, and certainly not a plane) in a 3 dimensional space. The same quantities, measured for the stars in elliptical galaxies, echo the parent halo quantities but fan out into a plane (probably with a small but finite thickness). The stellar quantities are affected by at least two dimensionless numbers -- call them efficiency and contraction -- that show both systematic variation with scale and stochastic variation at fixed scale. The virial theorem implies that stellar velocity dispersion is a good proxy for that of the parent halo (and hence its mass and radius), subject to caveats for low mass halos. Our argument elaborates on that of http://www.arxiv.org/pdf/1508.02358 .
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Generalized Structural Scaling Relations of Galaxies
I review generalized structural scaling relations of galaxies involving masses, sizes, shapes and galaxy kinematics, placing particular emphasis on results obtained with recent integral-field spectroscopic surveys.
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I review generalized structural scaling relations of galaxies involving masses, sizes, shapes and galaxy kinematics, placing particular emphasis on results obtained with recent integral-field spectroscopic surveys.
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Variation in the stellar mass - halo mass relation
Most galaxies obey tight scaling relations, including a well-defined relation between the total mass in stars and the total mass in dark matter. I will present recent results on the kinematics of several recently discovered Milky Way-sized "ultra-diffuse" galaxies. These objects seem to break scaling relations that had been established for previously studied galaxy populations, and they possibly provide unique information on aspects of dark matter.
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Most galaxies obey tight scaling relations, including a well-defined relation between the total mass in stars and the total mass in dark matter. I will present recent results on the kinematics of several recently discovered Milky Way-sized "ultra-diffuse" galaxies. These objects seem to break scaling relations that had been established for previously studied galaxy populations, and they possibly provide unique information on aspects of dark matter.
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Disk galaxy scaling relations in the LSST/SKA era
Taranu et al. 2017 introduced a new method for fully self-consistent dynamical modeling of galaxies including a stellar bulge and disk and a dark matter halo, simultaneously fitting imaging and integral field spectroscopy. Using Bayesian methods and a full generative model, our code provides robust estimates of the mass profiles and structural parameters of both baryonic and dark components, as well as the total baryonic angular momentum. I will present new constraints on disk galaxy scaling relations using integral field spectroscopy from the SAMI galaxy survey, including both spiral galaxies and disky early-type galaxies (i.e. S0s). Lastly, I will discuss the prospects for applying this method to future multiwavelength data across the southern sky, including LSST and WFIRST/Euclid imaging, spectroscopy from 4MOST and 21cm HI observations from the SKA, potentially covering hundreds of thousands of galaxies to z=0.1 and beyond.
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Taranu et al. 2017 introduced a new method for fully self-consistent dynamical modeling of galaxies including a stellar bulge and disk and a dark matter halo, simultaneously fitting imaging and integral field spectroscopy. Using Bayesian methods and a full generative model, our code provides robust estimates of the mass profiles and structural parameters of both baryonic and dark components, as well as the total baryonic angular momentum. I will present new constraints on disk galaxy scaling relations using integral field spectroscopy from the SAMI galaxy survey, including both spiral galaxies and disky early-type galaxies (i.e. S0s). Lastly, I will discuss the prospects for applying this method to future multiwavelength data across the southern sky, including LSST and WFIRST/Euclid imaging, spectroscopy from 4MOST and 21cm HI observations from the SKA, potentially covering hundreds of thousands of galaxies to z=0.1 and beyond.
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Galaxy clocks and other star forming disk galaxy scaling relations
I will demonstrate that disk galaxies, from the smallest dwarf irregulars to the largest spirals, have the same orbital period of 1 Gyr at their outskirts. I will show how this result, along with a simple model of disks maintaining a constant stability, allows us to explain other scaling relations of star forming galaxies such as the usefulness of HI for tracing dark matter, and the constant scaling between star formation and HI content.
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I will demonstrate that disk galaxies, from the smallest dwarf irregulars to the largest spirals, have the same orbital period of 1 Gyr at their outskirts. I will show how this result, along with a simple model of disks maintaining a constant stability, allows us to explain other scaling relations of star forming galaxies such as the usefulness of HI for tracing dark matter, and the constant scaling between star formation and HI content.
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Using two billion spectra of the sky to study dark matter and dark energy
I will present the first data and results from the Hobby-Eberly Telescope Dark Energy Experiment. This survey will run for five years, using a suite of spectrographs fed by 35,000 fibers on the 10-meter HET. The survey has started. The primary goal is to measure the expansion rate of the universe to better than 1% accuracy at z=2.4, and we will also provide significant measures of the dark matter profiles in nearby large galaxies.
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I will present the first data and results from the Hobby-Eberly Telescope Dark Energy Experiment. This survey will run for five years, using a suite of spectrographs fed by 35,000 fibers on the 10-meter HET. The survey has started. The primary goal is to measure the expansion rate of the universe to better than 1% accuracy at z=2.4, and we will also provide significant measures of the dark matter profiles in nearby large galaxies.
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Taipan: a massive redshift and peculiar velocity survey to study dark matter and gravity in the local Universe
The recently begun Taipan survey of the local Universe will measure redshifts for 2 million galaxies and peculiar velocities for 50-100,000 galaxies over 2p steradians. The main scientific goals are: (i) to measure the local expansion rate, H0, to 1% and the growth rate of structure to 5%; (ii) to make the most extensive map of the mass distribution and motions in the local Universe, using peculiar velocities based on Fundamental Plane distances to enable sensitive tests of gravitational physics; and (iii) to deliver a legacy sample of nearby galaxies for studying galaxy scaling relations as a function of mass and environment, complementing current and planned southern sky surveys from the optical to the radio. I will summarise survey plans, describe how results on scaling relations from the SAMI IFU survey refined the peculiar velocity survey, and report the current status of the Taipan observations.
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The recently begun Taipan survey of the local Universe will measure redshifts for 2 million galaxies and peculiar velocities for 50-100,000 galaxies over 2p steradians. The main scientific goals are: (i) to measure the local expansion rate, H0, to 1% and the growth rate of structure to 5%; (ii) to make the most extensive map of the mass distribution and motions in the local Universe, using peculiar velocities based on Fundamental Plane distances to enable sensitive tests of gravitational physics; and (iii) to deliver a legacy sample of nearby galaxies for studying galaxy scaling relations as a function of mass and environment, complementing current and planned southern sky surveys from the optical to the radio. I will summarise survey plans, describe how results on scaling relations from the SAMI IFU survey refined the peculiar velocity survey, and report the current status of the Taipan observations.
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Constraining the nature of dark matter using the first galaxies
Annihilating (and decaying) dark matter models include some of the leading dark matter candidates proposed today. Injected energy from these dark matter interactions provide not only an additional source of heating and ionisation of the interstellar medium but could also change the evolution of the first stars and galaxies. These changes to canonical galaxy models maybe detectable in the 21cm emission line from neutral Hydrogen or wider, high redshift galaxy surveys. The recent 21cm detection by EDGES has demonstrated the important implications for dark matter particle parameters that can be derived from these results. Future surveys will no doubt offer further invaluable insights into the fundamental nature of dark matter, including the prospects for non-gravitational interactions.
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Annihilating (and decaying) dark matter models include some of the leading dark matter candidates proposed today. Injected energy from these dark matter interactions provide not only an additional source of heating and ionisation of the interstellar medium but could also change the evolution of the first stars and galaxies. These changes to canonical galaxy models maybe detectable in the 21cm emission line from neutral Hydrogen or wider, high redshift galaxy surveys. The recent 21cm detection by EDGES has demonstrated the important implications for dark matter particle parameters that can be derived from these results. Future surveys will no doubt offer further invaluable insights into the fundamental nature of dark matter, including the prospects for non-gravitational interactions.
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Summary of Direct Detection Experiments
The experimental quest for the direct detection of dark matter particles has undergone significant advantages in the past few years. There have been many new results released and there are even more prospects for future detectors. The number of experiments (and even techniques) continues to expand, making any summary difficult. A very brief "state of the field" will be presented as well as some discussion of the direction for the next generation and beyond.
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The experimental quest for the direct detection of dark matter particles has undergone significant advantages in the past few years. There have been many new results released and there are even more prospects for future detectors. The number of experiments (and even techniques) continues to expand, making any summary difficult. A very brief "state of the field" will be presented as well as some discussion of the direction for the next generation and beyond.
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A Radio Astronomy Search for Axion Dark Matter
A number of laboratory searches are underway for cold dark matter (CDM) axions, relativistic solar axions, and ultra-light axions. The interest in axions as CDM candidates is motivated by their potential to account for all of the inferred value of OmegaDM ~ 0.26 in the standard LambdaCDM model. Indeed, the value of OmegaDM ~ 0.26 could be set by the axion mass. We investigate the possibility of complementing existing axion search experiments with radio telescope observations in an attempt to detect axion conversion in astrophysical magnetic fields. Searching for a CDM axion signal from a large-scale astrophysical environment provides new challenges, with the magnetic field structure playing a crucial role in both the rate of interaction and the properties of the observed photon. With a predicted frequency in the radio band (200 MHz–200 GHz) and a distinguishable spectral profile, next-generation radio telescopes may offer new opportunities for detection.
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A number of laboratory searches are underway for cold dark matter (CDM) axions, relativistic solar axions, and ultra-light axions. The interest in axions as CDM candidates is motivated by their potential to account for all of the inferred value of OmegaDM ~ 0.26 in the standard LambdaCDM model. Indeed, the value of OmegaDM ~ 0.26 could be set by the axion mass. We investigate the possibility of complementing existing axion search experiments with radio telescope observations in an attempt to detect axion conversion in astrophysical magnetic fields. Searching for a CDM axion signal from a large-scale astrophysical environment provides new challenges, with the magnetic field structure playing a crucial role in both the rate of interaction and the properties of the observed photon. With a predicted frequency in the radio band (200 MHz–200 GHz) and a distinguishable spectral profile, next-generation radio telescopes may offer new opportunities for detection.
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The Magic Scale of Galaxies and the KS Relation from Supernova Feedback
I will address the role of supernova feedback in determining the characteristic mass scale of efficient galaxy formation and the galaxy scaling relations. In particular, I will show that the Kennicutt-Schmidt relation of star-formation rate density and gas density arises naturally from the self-regulation of the star formation via supernova feedback, solely based on the standard physics of supernova remnants.
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I will address the role of supernova feedback in determining the characteristic mass scale of efficient galaxy formation and the galaxy scaling relations. In particular, I will show that the Kennicutt-Schmidt relation of star-formation rate density and gas density arises naturally from the self-regulation of the star formation via supernova feedback, solely based on the standard physics of supernova remnants.
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Galaxy-Black Hole Scaling Relations in the Simba Galaxy Formation Simulations
The physics driving the co-evolution of galaxies and their central black holes remains poorly understood. Recent progress on including black hole growth and feedback into hydrodynamic simulations has shown promise at reproducing key observables, but the required subgrid prescriptions required are not necessarily concordant with observed feedback. We present a new suite of simulations called Simba (the descendant of Mufasa) that includes novel prescriptions for black hole growth using torque-limited accretion, and black hole feedback using bipolar kinetic outflows. Torque-limited accretion promisingly yields black hole growth in concert with galaxies as observed without requiring self-regulation as in the commonly-used Bondi case. Owing to this, we are able to implement a bipolar kinetic scheme for black hole feedback as seen in real AGN outflows, which successfully produces a population of massive quenched galaxies. I will present preliminary results from Simba, focusing on the origin and evolution of scaling relations between galaxies, black holes, and circumgalactic gas.
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The physics driving the co-evolution of galaxies and their central black holes remains poorly understood. Recent progress on including black hole growth and feedback into hydrodynamic simulations has shown promise at reproducing key observables, but the required subgrid prescriptions required are not necessarily concordant with observed feedback. We present a new suite of simulations called Simba (the descendant of Mufasa) that includes novel prescriptions for black hole growth using torque-limited accretion, and black hole feedback using bipolar kinetic outflows. Torque-limited accretion promisingly yields black hole growth in concert with galaxies as observed without requiring self-regulation as in the commonly-used Bondi case. Owing to this, we are able to implement a bipolar kinetic scheme for black hole feedback as seen in real AGN outflows, which successfully produces a population of massive quenched galaxies. I will present preliminary results from Simba, focusing on the origin and evolution of scaling relations between galaxies, black holes, and circumgalactic gas.
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Calibrating the Black Hole Mass Scaling Relations
The close correlations between black holes (BHs) and their host-galaxies is suggestive of their co-evolution. From a unique sample of ~100 local type-1 AGNs spanning a wide range of BH masses (MBH), morphologies, and stellar masses, we build a robust baseline of the MBH scaling relations, combining spatially-resolved Keck spectroscopy with HST/WFC3 and Gemini/NIRI imaging. We establish the fundamental MBH relationship and determine whether the scaling relations are universal or depend on other parameters such as (minor) mergers, (pseudo) bulges, and/or bars. This identifies the driving force behind the relations, hierarchical assembly vs. AGN feedback. Using VLT/MUSE and Keck/KCWI spatially-resolved kinematics of reverberation-mapped AGNs, we determine the slope of the MBH-sigma relation, its intercept and scatter, constrain the average f factor, and identify dependencies of the relation on luminosity, Eddington ratio and host-galaxy morphology. This builds the crucial low-z anchor for the determination of MBH in AGNs throughout the Universe.
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The close correlations between black holes (BHs) and their host-galaxies is suggestive of their co-evolution. From a unique sample of ~100 local type-1 AGNs spanning a wide range of BH masses (MBH), morphologies, and stellar masses, we build a robust baseline of the MBH scaling relations, combining spatially-resolved Keck spectroscopy with HST/WFC3 and Gemini/NIRI imaging. We establish the fundamental MBH relationship and determine whether the scaling relations are universal or depend on other parameters such as (minor) mergers, (pseudo) bulges, and/or bars. This identifies the driving force behind the relations, hierarchical assembly vs. AGN feedback. Using VLT/MUSE and Keck/KCWI spatially-resolved kinematics of reverberation-mapped AGNs, we determine the slope of the MBH-sigma relation, its intercept and scatter, constrain the average f factor, and identify dependencies of the relation on luminosity, Eddington ratio and host-galaxy morphology. This builds the crucial low-z anchor for the determination of MBH in AGNs throughout the Universe.
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The evolution of black-hole properties and the implications for galaxy quenching
I will discuss a new study based on the Henriques et al. (2015) version of the Munich galaxy formation model investigating why there is a halo/stellar mass scale above which galaxies are quenched, that is roughly constant with redshift, and that is almost coincident with the scale at which baryon conversion into stars is almost at a maximum. This model assumes that central galaxies are quenched by AGN feedback when hot halo gas accretes onto a massive enough central black hole. Nevertheless, we find that it is supernova (SN) feedback that sets both mass scales. In massive objects, SN feedback is unable to eject gas from galaxy haloes. This increases the amount of hot halo gas, which in turn increases the cooling rate onto the central galaxy and hence its cold gas content, leading into a phase of intense star formation. The large cold gas reservoir also fuels the central black hole which soon becomes massive enough to produce strong AGN feedback and suppress the supply of new fuel for star formation. The transition between a gas-poor (most gas is ejected by supernovae) into a gas rich phase in galaxy evolution can be clearly seen in the black hole-bulge/stellar mass relation: almost no black hole growth at low galaxy mass (flat slope), and rapid black hole growth at high-masses (steep slope).I’ll compare the results of different model variations with observed halo-stellar mass relations, black hole-stellar mass relations, quenched fractions and stellar mass functions at different redshifts and show that these conclusions are independent of the hot/cold mode accretion state of the halo and the black hole and AGN feedback implementations as long as black holes grow predominately via cold gas accretion.
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I will discuss a new study based on the Henriques et al. (2015) version of the Munich galaxy formation model investigating why there is a halo/stellar mass scale above which galaxies are quenched, that is roughly constant with redshift, and that is almost coincident with the scale at which baryon conversion into stars is almost at a maximum. This model assumes that central galaxies are quenched by AGN feedback when hot halo gas accretes onto a massive enough central black hole. Nevertheless, we find that it is supernova (SN) feedback that sets both mass scales. In massive objects, SN feedback is unable to eject gas from galaxy haloes. This increases the amount of hot halo gas, which in turn increases the cooling rate onto the central galaxy and hence its cold gas content, leading into a phase of intense star formation. The large cold gas reservoir also fuels the central black hole which soon becomes massive enough to produce strong AGN feedback and suppress the supply of new fuel for star formation. The transition between a gas-poor (most gas is ejected by supernovae) into a gas rich phase in galaxy evolution can be clearly seen in the black hole-bulge/stellar mass relation: almost no black hole growth at low galaxy mass (flat slope), and rapid black hole growth at high-masses (steep slope).I’ll compare the results of different model variations with observed halo-stellar mass relations, black hole-stellar mass relations, quenched fractions and stellar mass functions at different redshifts and show that these conclusions are independent of the hot/cold mode accretion state of the halo and the black hole and AGN feedback implementations as long as black holes grow predominately via cold gas accretion.
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Galaxy Scaling Relations in Cosmological Hydrodynamical Simulations: The Importance of AGN Feedback
Reproducing the observed galaxy scaling relations in simulations of galaxy formation has been a challenge for many years. I will present the scaling relations found for disk and spheroidal galaxies from the state-of-the-art cosmological hydrodynamical simulation Magneticum, and demonstrate the importance of the AGN feedback for establishing these scaling relations. I will also show how the AGN feedback influences the interplay between the baryonic and the dark matter component of galaxies in LambdaCDM cosmology, and the consequences that arise from this for observations. Finally, I will discuss the caveats that are still present in successfully establishing galaxy scaling relations in modern cosmological hydrodynamical simulations, and what we can learn from this about galaxy formation processes.
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Reproducing the observed galaxy scaling relations in simulations of galaxy formation has been a challenge for many years. I will present the scaling relations found for disk and spheroidal galaxies from the state-of-the-art cosmological hydrodynamical simulation Magneticum, and demonstrate the importance of the AGN feedback for establishing these scaling relations. I will also show how the AGN feedback influences the interplay between the baryonic and the dark matter component of galaxies in LambdaCDM cosmology, and the consequences that arise from this for observations. Finally, I will discuss the caveats that are still present in successfully establishing galaxy scaling relations in modern cosmological hydrodynamical simulations, and what we can learn from this about galaxy formation processes.
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Scaling relations in the NIHAO project with AGN feedback
The NIHAO project (Numerical Investigation of a Hundred Astrophysical Objects) is a set of 100 cosmological high resolution zoom-in simulations of galaxies, whose halos range from dwarf to Milky Way masses. I will present our current work to include black hole formation, accretion and AGN feedback into our simulations and to extend their mass range from Milky Way to elliptical masses. I will furthermore show how NIHAO compares with various scaling relations known from observations, how AGN feedback affects these scaling relations, especially black hole scaling relations, and how AGN feedback affects the galaxies' dark matter profiles.
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The NIHAO project (Numerical Investigation of a Hundred Astrophysical Objects) is a set of 100 cosmological high resolution zoom-in simulations of galaxies, whose halos range from dwarf to Milky Way masses. I will present our current work to include black hole formation, accretion and AGN feedback into our simulations and to extend their mass range from Milky Way to elliptical masses. I will furthermore show how NIHAO compares with various scaling relations known from observations, how AGN feedback affects these scaling relations, especially black hole scaling relations, and how AGN feedback affects the galaxies' dark matter profiles.
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Revisiting the black hole - galaxy scaling relations with the SMASHING sample
Over hundred massive black hole (MBH) mass measurements of local galaxies have revealed strong correlations with different properties of their host galaxy bulge. However, determining MBH masses is a challenging procedure and possible biases need to be recovered before properly understanding the underlying physics. I present two projects to address the following questions: Do high-mass and low-mass black holes follow the same scaling relations? Does the variety of mass measurement methods force an additional bias on the scaling relations? Therefore, I present our SMASHING sample of 20 early-type galaxies which expand the scaling relations on both the high and low mass end. Then, I show the comparison of two independent MBH determinations from stellar kinematics (MUSE) and the novel molecular gas kinematics technique (ALMA), taking special care in revisiting the associated measurement errors, specifically, the systematics associated with the dynamical methods, and the general accuracy of MBH mass measurements.
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Over hundred massive black hole (MBH) mass measurements of local galaxies have revealed strong correlations with different properties of their host galaxy bulge. However, determining MBH masses is a challenging procedure and possible biases need to be recovered before properly understanding the underlying physics. I present two projects to address the following questions: Do high-mass and low-mass black holes follow the same scaling relations? Does the variety of mass measurement methods force an additional bias on the scaling relations? Therefore, I present our SMASHING sample of 20 early-type galaxies which expand the scaling relations on both the high and low mass end. Then, I show the comparison of two independent MBH determinations from stellar kinematics (MUSE) and the novel molecular gas kinematics technique (ALMA), taking special care in revisiting the associated measurement errors, specifically, the systematics associated with the dynamical methods, and the general accuracy of MBH mass measurements.
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Galactic dynamics, feedback and dark matter at z~0.7-2.7
I will discuss constraints on galactic dynamics, dark matter distributions and feedback of star forming disk galaxies at z~0.7-2.7 obtained from the SINS/zC-SINF and KMOS-3D near-IR IFU surveys at the VLT.
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I will discuss constraints on galactic dynamics, dark matter distributions and feedback of star forming disk galaxies at z~0.7-2.7 obtained from the SINS/zC-SINF and KMOS-3D near-IR IFU surveys at the VLT.
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Evolution of dynamical scaling relations to z=1
The LEGA-C spectroscopic survey with VLT/VIMOS represents the first substantial investment in obtaining high-resolution continuum spectroscopy of high-redshift galaxies. For the first time we can access information on the stellar population characteristics and kinematics of z>0.5 galaxies of all types. I will show how the dynamical scaling relations evolved over the past 7 Gyr and how this evolution connects with the evolutionary histories of individual galaxies as inferred from their spectra.
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The LEGA-C spectroscopic survey with VLT/VIMOS represents the first substantial investment in obtaining high-resolution continuum spectroscopy of high-redshift galaxies. For the first time we can access information on the stellar population characteristics and kinematics of z>0.5 galaxies of all types. I will show how the dynamical scaling relations evolved over the past 7 Gyr and how this evolution connects with the evolutionary histories of individual galaxies as inferred from their spectra.
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Constraining the dark matter content in high-z star-forming galaxies through the evolution of the Tully-Fisher relation from z~2.3 to z~0.9
The multiplexing capabilities of instruments such as KMOS@VLT have facilitated a huge leap forward in investigating galaxy scaling relations at high redshift. We present the evolution of the stellar and baryonic mass Tully-Fisher relations of 135 massive, star-forming galaxies from z~2.3 to z~0.9, based on data from the KMOS^3D survey which targets the ionized gas emission of more than 700 galaxies. With gas-to-stellar mass ratios decreasing towards lower redshift, we find that the contribution of dark matter to the dynamical mass on galactic scales increases. This result is in line with independent constraints obtained from detailed modeling of the kinematics of individual high-z galaxies extending to large radii of ~15-20 kpc.
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The multiplexing capabilities of instruments such as KMOS@VLT have facilitated a huge leap forward in investigating galaxy scaling relations at high redshift. We present the evolution of the stellar and baryonic mass Tully-Fisher relations of 135 massive, star-forming galaxies from z~2.3 to z~0.9, based on data from the KMOS^3D survey which targets the ionized gas emission of more than 700 galaxies. With gas-to-stellar mass ratios decreasing towards lower redshift, we find that the contribution of dark matter to the dynamical mass on galactic scales increases. This result is in line with independent constraints obtained from detailed modeling of the kinematics of individual high-z galaxies extending to large radii of ~15-20 kpc.
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Does Time and Environment affect the Stellar-Mass Tully-Fisher Relation?
Galaxy internal kinematics is one of the most promising tools to investigate galaxy formation and evolution since it traces both luminous and dark matter distributions. The stellar-mass Tully-Fisher relation (smTFR) is one such tool, providing constraints on the interplay between galaxy stellar and total (dynamical) mass. I will present, first, results obtained within the spectroscopic survey HR-COSMOS at redshift 0<z<1.2 on the evolution of the smTFR and the stellar-to-dynamical mass ratio of field galaxies over a large baseline in cosmic time. I will then compare these results to those from the ORELSE survey, a massive photometric/spectroscopic campaign mapping 16 large-scale structures at 0.6<z<1.3 and probing a wide range of galaxy densities and physical conditions. I will show through these comparisons that the smTFR is remarkably stable over both cosmic time and environment, emphasizing its utility in understanding the total mass assembly of a large range of galaxies throughout the universe.
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Galaxy internal kinematics is one of the most promising tools to investigate galaxy formation and evolution since it traces both luminous and dark matter distributions. The stellar-mass Tully-Fisher relation (smTFR) is one such tool, providing constraints on the interplay between galaxy stellar and total (dynamical) mass. I will present, first, results obtained within the spectroscopic survey HR-COSMOS at redshift 0<z<1.2 on the evolution of the smTFR and the stellar-to-dynamical mass ratio of field galaxies over a large baseline in cosmic time. I will then compare these results to those from the ORELSE survey, a massive photometric/spectroscopic campaign mapping 16 large-scale structures at 0.6<z<1.3 and probing a wide range of galaxy densities and physical conditions. I will show through these comparisons that the smTFR is remarkably stable over both cosmic time and environment, emphasizing its utility in understanding the total mass assembly of a large range of galaxies throughout the universe.
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Faint End of the Group Mass Function
Galaxy groups are a familiar component of large scale structure in the mass range down to that of the Local Group but what are the properties of groups at smaller masses? Such entities can only reliably be identified very nearby where we have an increasingly complete census of galaxies and group properties thanks to accurate distances from the tip of the red giant method. The group mass function can be reliably extended down to group masses of 10^10 solar masses, two orders of magnitude below that of the Local Group.
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Galaxy groups are a familiar component of large scale structure in the mass range down to that of the Local Group but what are the properties of groups at smaller masses? Such entities can only reliably be identified very nearby where we have an increasingly complete census of galaxies and group properties thanks to accurate distances from the tip of the red giant method. The group mass function can be reliably extended down to group masses of 10^10 solar masses, two orders of magnitude below that of the Local Group.
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The stellar mass Tully-Fisher relation from gas and stars since z~1.
The stellar mass Tully-Fisher relation is a powerful tool to understand the evolution of galaxy disks in the context of dark matter halo growth. Models and observations suggest its scaling has evolved over time, but a clear interpretation is hampered by systematic measurement uncertainties and selection effects. More fundamentally, the question has arisen of how to take into account the increased gas fractions and larger contributions from random motions in galaxies at higher redshift. Using 20-hour deep spectra of over 100 galaxies from the VLT/VIMOS LEGA-C survey, I will present new constraints on the scaling of the Tully-Fisher relation at z~1 for galaxies traced, as usual, by ionized gas, but now cross-checked for the first time at high redshift with dynamical mass models based on stellar rotation curves, also produced by the LEGA-C survey.
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The stellar mass Tully-Fisher relation is a powerful tool to understand the evolution of galaxy disks in the context of dark matter halo growth. Models and observations suggest its scaling has evolved over time, but a clear interpretation is hampered by systematic measurement uncertainties and selection effects. More fundamentally, the question has arisen of how to take into account the increased gas fractions and larger contributions from random motions in galaxies at higher redshift. Using 20-hour deep spectra of over 100 galaxies from the VLT/VIMOS LEGA-C survey, I will present new constraints on the scaling of the Tully-Fisher relation at z~1 for galaxies traced, as usual, by ionized gas, but now cross-checked for the first time at high redshift with dynamical mass models based on stellar rotation curves, also produced by the LEGA-C survey.
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The Efficiency of Star Formation and the Stellar Mass-Halo Mass Relation in Massive Dark Matter Halos
Several long-standing problems in galaxy evolution hinge on an accurate census of the stellar mass content of central (so-called brightest cluster) galaxies, including measurements of the star formation efficiency in massive dark matter halos, the relative importance of supernova and AGN feedback in numerical simulations, and tests of the inside-out formation of spheroidal galaxies. However, even relatively straightforward measurements of the massive end of the stellar mass function at z~0.1 remain wildly discrepant. To address these issues, we measure the stellar mass density profiles and integrated stellar masses of a sample of more than 50,000 central galaxies at z<0.5 using state-of-the-art stellar population synthesis fitting techniques and deep optical and mid-infrared imaging obtained as part of the Legacy Surveys (http://legacysurvey.org). We find a non-negligible reservoir of stellar mass in the low surface-brightness outer envelopes of the central galaxies in our sample, and discuss the wide-ranging implications of our results for the efficiency of star formation and the intensity of AGN feedback in massive dark matter halos.
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Several long-standing problems in galaxy evolution hinge on an accurate census of the stellar mass content of central (so-called brightest cluster) galaxies, including measurements of the star formation efficiency in massive dark matter halos, the relative importance of supernova and AGN feedback in numerical simulations, and tests of the inside-out formation of spheroidal galaxies. However, even relatively straightforward measurements of the massive end of the stellar mass function at z~0.1 remain wildly discrepant. To address these issues, we measure the stellar mass density profiles and integrated stellar masses of a sample of more than 50,000 central galaxies at z<0.5 using state-of-the-art stellar population synthesis fitting techniques and deep optical and mid-infrared imaging obtained as part of the Legacy Surveys (http://legacysurvey.org). We find a non-negligible reservoir of stellar mass in the low surface-brightness outer envelopes of the central galaxies in our sample, and discuss the wide-ranging implications of our results for the efficiency of star formation and the intensity of AGN feedback in massive dark matter halos.
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The impact of “pre-processing” on the galaxy mass-size scaling relation
Are the observed scaling relations due to the timing and physics of cosmological structure formation or due to baryonic physics? To answer this question we explore the galaxy stellar mass-size relation of 560 spectroscopic members (down to 10^8.5Msol) in a massive galaxy cluster at z=0.44 (Kuchner+17). Our observations probe the infall region out to 3 virial radii which is central to the topical question of “pre-processing”. The smoking gun of this “pre-processing” are transitional objects, like passive spirals, whose stellar populations and morphologies indicate a recent change in star formation and/or dynamical history. We find a large number of this virialized population at distinct locations. We are able to show that the manifestation of the size distribution of the cluster galaxies is due to an outer disk-fading and possible bulge growth that accompanies the varying fraction of star-forming and quiescent galaxies.
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Are the observed scaling relations due to the timing and physics of cosmological structure formation or due to baryonic physics? To answer this question we explore the galaxy stellar mass-size relation of 560 spectroscopic members (down to 10^8.5Msol) in a massive galaxy cluster at z=0.44 (Kuchner+17). Our observations probe the infall region out to 3 virial radii which is central to the topical question of “pre-processing”. The smoking gun of this “pre-processing” are transitional objects, like passive spirals, whose stellar populations and morphologies indicate a recent change in star formation and/or dynamical history. We find a large number of this virialized population at distinct locations. We are able to show that the manifestation of the size distribution of the cluster galaxies is due to an outer disk-fading and possible bulge growth that accompanies the varying fraction of star-forming and quiescent galaxies.
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Impact of Halo Mass on Scaling Relations
I will present new results from the Hyper Suprime Cam Survey (Huang et al. 2017, 2018) characterizing the light profiles of several thousand super massive galaxies (log(M*)>11.6) to 100 kpc. The depth of HSC data enables us to measure surface mass density profiles to 100 kpc for individual galaxies without stacking. We show that super massive galaxies have a range of outer profiles and that on average massive galaxies exhibit more extended outer profiles than smaller galaxies. Using weak gravitational lensing, we also conclusively show that, at fixed stellar mass, the stellar profiles (and sizes) of massive galaxies depend on the masses of their dark matter haloes. I will discuss how these results can be interpreted in terms of the two phase formation scenario for massive galaxies. Finally, I will also discuss how these results provide key insight into the assembly process of massive galaxies as well as the impact of halo mass in setting scaling relations.
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I will present new results from the Hyper Suprime Cam Survey (Huang et al. 2017, 2018) characterizing the light profiles of several thousand super massive galaxies (log(M*)>11.6) to 100 kpc. The depth of HSC data enables us to measure surface mass density profiles to 100 kpc for individual galaxies without stacking. We show that super massive galaxies have a range of outer profiles and that on average massive galaxies exhibit more extended outer profiles than smaller galaxies. Using weak gravitational lensing, we also conclusively show that, at fixed stellar mass, the stellar profiles (and sizes) of massive galaxies depend on the masses of their dark matter haloes. I will discuss how these results can be interpreted in terms of the two phase formation scenario for massive galaxies. Finally, I will also discuss how these results provide key insight into the assembly process of massive galaxies as well as the impact of halo mass in setting scaling relations.
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Scaling relations from weak lensing
Galaxy clusters are potentially powerful probes of cosmology if we can relate their observed properties to the underlying mass distribution. Weak gravitational lensing has become a key tool in determining these scaling relations, which in turn can help improve our understanding of galaxy formation as a function of environment. These studies can now be extended to higher redshifts, and to lower masses through stacking analyses. Finally these data can be used to study the dark matter halos of galaxies as a function of environment. In this talk I will highlight some of the recent developments in this rapidly developing field.
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Galaxy clusters are potentially powerful probes of cosmology if we can relate their observed properties to the underlying mass distribution. Weak gravitational lensing has become a key tool in determining these scaling relations, which in turn can help improve our understanding of galaxy formation as a function of environment. These studies can now be extended to higher redshifts, and to lower masses through stacking analyses. Finally these data can be used to study the dark matter halos of galaxies as a function of environment. In this talk I will highlight some of the recent developments in this rapidly developing field.
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Extending galaxy scaling relations to include the dark matter halo, using weak gravitational lensing
Galaxy scaling relations based on dynamics, such as the Faber-Jackson, Fundamental Plane and Tully-Fisher relations, have revolutionized our understanding of galaxy formation. These relations, however, probe only the *inner* regions of the dark matter haloes, where baryonic kinematic tracers are available. Weak gravitational lensing allows us to measure the mass of the entire DM halo and link its properties to those of the baryons that it hosts. I will describe recent results from weak lensing surveys, particularly from the CFHTLenS collaboration. These studies allow us to gain new insights into galaxy formation and evolution, by studying the links between DM halo and the galaxy stellar mass, size and environment, and their evolution with cosmic time.
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Galaxy scaling relations based on dynamics, such as the Faber-Jackson, Fundamental Plane and Tully-Fisher relations, have revolutionized our understanding of galaxy formation. These relations, however, probe only the *inner* regions of the dark matter haloes, where baryonic kinematic tracers are available. Weak gravitational lensing allows us to measure the mass of the entire DM halo and link its properties to those of the baryons that it hosts. I will describe recent results from weak lensing surveys, particularly from the CFHTLenS collaboration. These studies allow us to gain new insights into galaxy formation and evolution, by studying the links between DM halo and the galaxy stellar mass, size and environment, and their evolution with cosmic time.
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Scaling relations and feedback at low masses and early cosmic times
What sets the cosmic epoch and the mass scale at which the Hubble sequence emerges? How and why do scaling relations such as Tully-Fisher and mass-metallicity evolve over time? What causes the discrepancy between observations and theoretical expectations for cold dark matter density profiles in dwarf galaxies? Addressing these questions requires spatially resolved spectrophotometric data reaching galaxies at low mass and high redshifts. I will discuss observations of magnified, gravitationally lensed galaxies uniquely probing the relevant scales at z=1-3. Measurements of kinematics, metallicities, and outflow properties together show that energetic feedback from star formation has a dramatic effect on the structure and composition of low-mass galaxies and their associated scaling relations. This feedback may destroy gaseous disks and alter dark matter density profiles at the lowest observed masses (Mstar < 10^9 Msun), as shown by the data and comparison with cosmological simulations.
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What sets the cosmic epoch and the mass scale at which the Hubble sequence emerges? How and why do scaling relations such as Tully-Fisher and mass-metallicity evolve over time? What causes the discrepancy between observations and theoretical expectations for cold dark matter density profiles in dwarf galaxies? Addressing these questions requires spatially resolved spectrophotometric data reaching galaxies at low mass and high redshifts. I will discuss observations of magnified, gravitationally lensed galaxies uniquely probing the relevant scales at z=1-3. Measurements of kinematics, metallicities, and outflow properties together show that energetic feedback from star formation has a dramatic effect on the structure and composition of low-mass galaxies and their associated scaling relations. This feedback may destroy gaseous disks and alter dark matter density profiles at the lowest observed masses (Mstar < 10^9 Msun), as shown by the data and comparison with cosmological simulations.
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The distribution of luminous and dark matter within galaxies: insights from the IllustrisTNG simulations
The distribution of luminous and dark matter within galaxies: insights from the IllustrisTNG simulations. The IllustrisTNG simulations (www.tng-project.org) are a novel laboratory to explore galaxy physics and to quantify the assembly and evolution of galaxy populations across an unprecedented range of halo masses, environments, evolutionary stages and cosmic times. IllustrisTNG is an ongoing program of large cosmological volume simulations where gravity, magnetohydrodynamics, and prescriptions for star formation, stellar evolution, metal enrichment, gas cooling/heating, galactic outflows and BH feedback are all taken into account within the LCDM cosmology. In the talk, I will review how and if the IllustrisTNG model reproduces basic galaxy scaling relations, by highlighting which ingredients are self-consistently included in our modelling and where improvements are instead required. I will hence focus on what we are learning with IllustrisTNG on two particular questions. On the one side, a tight scaling relation is known to hold between stellar mass and total halo mass for objects above the group mass scale (> 10^13 Msun). Even more powerfully, we find that halo mass alone is a good predictor for the whole stellar mass profile of massive galaxies, beyond the inner few kilo parsecs and all the way out to the outermost regions of the dark matter halo: on average such stellar profiles can be reconstructed given a single-mass measurement of the galaxy or its halo. On the other side, IllustrisTNG suggests that the dark-matter density profiles of haloes are modified in the presence of baryons in comparison to the NFW or Einasto functional forms expected from gravity-only calculations. In particular, our model predicts that the dark-matter halo concentration vs. mass relation is modified: from a monotonically decreasing relation with total halo mass in gravity-only models, to a relation that peaks at the characteristic ~10^12 Msun mass scale where dark matter haloes are contracted.
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The distribution of luminous and dark matter within galaxies: insights from the IllustrisTNG simulations. The IllustrisTNG simulations (www.tng-project.org) are a novel laboratory to explore galaxy physics and to quantify the assembly and evolution of galaxy populations across an unprecedented range of halo masses, environments, evolutionary stages and cosmic times. IllustrisTNG is an ongoing program of large cosmological volume simulations where gravity, magnetohydrodynamics, and prescriptions for star formation, stellar evolution, metal enrichment, gas cooling/heating, galactic outflows and BH feedback are all taken into account within the LCDM cosmology. In the talk, I will review how and if the IllustrisTNG model reproduces basic galaxy scaling relations, by highlighting which ingredients are self-consistently included in our modelling and where improvements are instead required. I will hence focus on what we are learning with IllustrisTNG on two particular questions. On the one side, a tight scaling relation is known to hold between stellar mass and total halo mass for objects above the group mass scale (> 10^13 Msun). Even more powerfully, we find that halo mass alone is a good predictor for the whole stellar mass profile of massive galaxies, beyond the inner few kilo parsecs and all the way out to the outermost regions of the dark matter halo: on average such stellar profiles can be reconstructed given a single-mass measurement of the galaxy or its halo. On the other side, IllustrisTNG suggests that the dark-matter density profiles of haloes are modified in the presence of baryons in comparison to the NFW or Einasto functional forms expected from gravity-only calculations. In particular, our model predicts that the dark-matter halo concentration vs. mass relation is modified: from a monotonically decreasing relation with total halo mass in gravity-only models, to a relation that peaks at the characteristic ~10^12 Msun mass scale where dark matter haloes are contracted.
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Contextualizing the time evolution of galaxy scaling relations with large-volume cosmological simulations
As extragalactic observations have pushed out to higher and higher redshifts, we have begun to see that the scaling relations we know and love are not necessarily static, but evolve over time just as galaxies do. What can the evolution OF galaxy scaling relations tell us about the the evolution of individual galaxies WITHIN those relations? Large-volume cosmological simulations like Illustris and EAGLE can connect the dots between redshifts and predict how galaxy populations evolve over time to produce these observed shifts in the statistics. I will present results from the Illustris simulation demonstrating that galaxies can take a large variety of evolutionary paths to reach similar states, complicating our interpretation of the observed shifts in scaling relations. The stochasticity in galaxy growth mirrors the stochastic growth of halo masses in dark-matter-only simulations like Millennium, indicating that this behavior is largely driven by the underlying dark matter.
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As extragalactic observations have pushed out to higher and higher redshifts, we have begun to see that the scaling relations we know and love are not necessarily static, but evolve over time just as galaxies do. What can the evolution OF galaxy scaling relations tell us about the the evolution of individual galaxies WITHIN those relations? Large-volume cosmological simulations like Illustris and EAGLE can connect the dots between redshifts and predict how galaxy populations evolve over time to produce these observed shifts in the statistics. I will present results from the Illustris simulation demonstrating that galaxies can take a large variety of evolutionary paths to reach similar states, complicating our interpretation of the observed shifts in scaling relations. The stochasticity in galaxy growth mirrors the stochastic growth of halo masses in dark-matter-only simulations like Millennium, indicating that this behavior is largely driven by the underlying dark matter.
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Simulating three alternatives to cold dark matter: light scalar fields, self-interacting particles, and warm thermal relics
While the Cold Dark Matter (CDM) paradigm works well in describing many cosmological observations, the detailed microphysics of the dark matter particle remains largely unconstrained by observations. Empirically, for example, there are few direct indications that the dark matter must be very cold (mass >> keV) or weakly interacting with itself. In this talk I will compare and contrast predictions using cosmological simulations of three alternative possibilities to CDM. 1) Self-Interacting Dark Matter with strong dark-matter self interactions; 2) Scalar Field Dark Matter with ultra-light mass (~ 1.e-22 eV); and 3) Warm Dark Matter with an intermediate mass (~keV). Each of these three models produce distinct predictions on non-linear scales that may be distinguished from CDM via astronomical observations.
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While the Cold Dark Matter (CDM) paradigm works well in describing many cosmological observations, the detailed microphysics of the dark matter particle remains largely unconstrained by observations. Empirically, for example, there are few direct indications that the dark matter must be very cold (mass >> keV) or weakly interacting with itself. In this talk I will compare and contrast predictions using cosmological simulations of three alternative possibilities to CDM. 1) Self-Interacting Dark Matter with strong dark-matter self interactions; 2) Scalar Field Dark Matter with ultra-light mass (~ 1.e-22 eV); and 3) Warm Dark Matter with an intermediate mass (~keV). Each of these three models produce distinct predictions on non-linear scales that may be distinguished from CDM via astronomical observations.
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Can dwarf galaxies discriminate cold dark matter and alternatives?
Dwarf satellite galaxies in the local group are tests of the cold dark matter paradigm through their measured density profiles, and are ideal targets for dark matter indirect detection searches. With current measurements of their profiles ambiguous, and with no clear particle annihilation signal, what is the future of these studies? I will discuss the current status of these observations, and highlight paths forward with future observatories, highlighting the impact of precision astrometry and 30m class telescopes.
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Dwarf satellite galaxies in the local group are tests of the cold dark matter paradigm through their measured density profiles, and are ideal targets for dark matter indirect detection searches. With current measurements of their profiles ambiguous, and with no clear particle annihilation signal, what is the future of these studies? I will discuss the current status of these observations, and highlight paths forward with future observatories, highlighting the impact of precision astrometry and 30m class telescopes.
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A conclusive test of cold dark matter
The "Lambda cold dark matter" cosmological model is one of the great achievements in Physics of the past thirty years. Theoretical predictions formulated in the 1980s turned out to agree remarkably well with measurements, performed decades later, of the galaxy distribution and the temperature structure of the microwave background radiation. Yet, these successes do not inform us directly about the nature of the dark matter. Indeed, there are competing (and controversial) claims that the dark matter might have already been discovered, either through the annihilation of cold, or the decay of warm, dark matter particles. In astrophysics the identity of the dark matter manifests itself clearly in the properties of dwarf galaxies, such as the satellites of the Milky Way. I will discuss predictions from cosmological simulations assuming cold and warm (in the form of sterile neutrinos) dark matter and show how astronomical observations can conclusively distinguish between the two.
The "Lambda cold dark matter" cosmological model is one of the great achievements in Physics of the past thirty years. Theoretical predictions formulated in the 1980s turned out to agree remarkably well with measurements, performed decades later, of the galaxy distribution and the temperature structure of the microwave background radiation. Yet, these successes do not inform us directly about the nature of the dark matter. Indeed, there are competing (and controversial) claims that the dark matter might have already been discovered, either through the annihilation of cold, or the decay of warm, dark matter particles. In astrophysics the identity of the dark matter manifests itself clearly in the properties of dwarf galaxies, such as the satellites of the Milky Way. I will discuss predictions from cosmological simulations assuming cold and warm (in the form of sterile neutrinos) dark matter and show how astronomical observations can conclusively distinguish between the two.
The Mass Discrepancy-Acceleration Relation: feedback, modified gravity, or baryon-dark matter interactions?
In this review, we show why the observed tightness of the Mass Discrepancy-Acceleration Relation (MDAR) poses a fine-tuning challenge to current models of galaxy formation. Whilst alternative gravity frameworks based on MOND reproduce it by construction, such theories struggle with reproducing the cosmological successes of LCDM. We then present two exotic DM models in which this relation would emerge naturally, whilst the cosmological successes of LCDM could be preserved. The first model is based on light DM particles which condense into a superfluid phase in the central regions of galaxy halos. The superfluid phonon excitations in turn couple to baryons and mediate an additional long-range force reproducing the MDAR. The second model is based on strong short-range (collisional) interactions between baryons and DM in which the product between the baryon-DM cross section and the typical energy exchanged in a collision is inversely proportional to the DM number density, leading to the MDAR as an equilbrium configuration. We discuss the distinctive predictions that such models make, which could allow to test them.
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In this review, we show why the observed tightness of the Mass Discrepancy-Acceleration Relation (MDAR) poses a fine-tuning challenge to current models of galaxy formation. Whilst alternative gravity frameworks based on MOND reproduce it by construction, such theories struggle with reproducing the cosmological successes of LCDM. We then present two exotic DM models in which this relation would emerge naturally, whilst the cosmological successes of LCDM could be preserved. The first model is based on light DM particles which condense into a superfluid phase in the central regions of galaxy halos. The superfluid phonon excitations in turn couple to baryons and mediate an additional long-range force reproducing the MDAR. The second model is based on strong short-range (collisional) interactions between baryons and DM in which the product between the baryon-DM cross section and the typical energy exchanged in a collision is inversely proportional to the DM number density, leading to the MDAR as an equilbrium configuration. We discuss the distinctive predictions that such models make, which could allow to test them.
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Self-interacting dark matter and small scale structure
It is unclear whether the cold dark matter paradigm is successful in describing the observed small scale structure of the Universe. I describe some of these tensions between theoretical predictions and observations and how self-interactions for dark matter may solve these issues. I discuss the implications for self-interactions for the observed diversity and uniformity of disk galaxies, as well as for observations of elliptical galaxies, groups, and clusters.
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It is unclear whether the cold dark matter paradigm is successful in describing the observed small scale structure of the Universe. I describe some of these tensions between theoretical predictions and observations and how self-interactions for dark matter may solve these issues. I discuss the implications for self-interactions for the observed diversity and uniformity of disk galaxies, as well as for observations of elliptical galaxies, groups, and clusters.
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Dark matter models with a power spectrum cutoff: then and now
A successful theory of dark matter must simultaneously explain, or at least be consistent with, observations across all times, from the formation of the first stars to the properties of our own Local Group. Some of the phenomena that feature faint galaxies have proved challenging for CDM, especially in the context of the failure to detect WIMPs conclusively in laboratory experiments. Faint galaxies are affected by the presence of a cutoff in the matter power spectrum, such as those generated in the ETHOS model of SIDM and the sterile neutrino model. In this talk I will discuss the impact of these power spectrum cutoffs at both ends of the galaxy formation story: at z~10 with the impact on the progress of reionisation, and then with the abundance and structure of the Local Group satellites. I will also outline progress on dark matter decay detection and lensing constraints.
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A successful theory of dark matter must simultaneously explain, or at least be consistent with, observations across all times, from the formation of the first stars to the properties of our own Local Group. Some of the phenomena that feature faint galaxies have proved challenging for CDM, especially in the context of the failure to detect WIMPs conclusively in laboratory experiments. Faint galaxies are affected by the presence of a cutoff in the matter power spectrum, such as those generated in the ETHOS model of SIDM and the sterile neutrino model. In this talk I will discuss the impact of these power spectrum cutoffs at both ends of the galaxy formation story: at z~10 with the impact on the progress of reionisation, and then with the abundance and structure of the Local Group satellites. I will also outline progress on dark matter decay detection and lensing constraints.
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Galaxy scaling relations for WDM models based on the empirical model Emerge
The nature of dark matter and its impact on galaxy scaling relations has been studied in detail with hydrodynamical simulations and semi-analytic models. The overall consensus of these studies is that the uncertainty in the predicted galaxy properties and scaling relations due to different dark matter models such as warm dark matter (m > 1keV) is smaller than the uncertainty in the adopted sub-grid models. I will present results from my new empirical model Emerge on galaxy scaling relations and clustering. The advantage of this approach is that the uncertainty in the baryonic physics can be marginalised over. We find that scaling relations that are a direct consequence of the stellar-to-halo mass relation change noticeably, which will be testable by surveys with next-generation telescopes. Interestingly however, the effect on galaxy clustering is rather limited, such that it will be difficult to test WDM models with clustering.
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The nature of dark matter and its impact on galaxy scaling relations has been studied in detail with hydrodynamical simulations and semi-analytic models. The overall consensus of these studies is that the uncertainty in the predicted galaxy properties and scaling relations due to different dark matter models such as warm dark matter (m > 1keV) is smaller than the uncertainty in the adopted sub-grid models. I will present results from my new empirical model Emerge on galaxy scaling relations and clustering. The advantage of this approach is that the uncertainty in the baryonic physics can be marginalised over. We find that scaling relations that are a direct consequence of the stellar-to-halo mass relation change noticeably, which will be testable by surveys with next-generation telescopes. Interestingly however, the effect on galaxy clustering is rather limited, such that it will be difficult to test WDM models with clustering.
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The SAMI Galaxy Survey: Gravitational Potential and Surface Density Drive Stellar Populations in Early-type Galaxies
The well-established correlations between the mass of a galaxy and the properties of its stars are considered evidence for mass driving the evolution of the stellar population. However, for our sample of 625 early-type galaxies (ETGs) with integral-field spectroscopy from the SAMI Galaxy Survey, compared to correlations with mass, the color—gravitational potential ($\Phi$), [Z/H]--$\Phi$, and age—surface density ($\Sigma$) relations show both smaller scatter and less residual trend with galaxy size. These results lead us to the following inferences: (1) the color--$\Phi$ diagram is a more precise tool for determining the developmental stage of the stellar population than the conventional color--$M$ diagram; and (2) gravitational potential is the primary regulator of global stellar metallicity, via its relation to the gas escape velocity.
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The well-established correlations between the mass of a galaxy and the properties of its stars are considered evidence for mass driving the evolution of the stellar population. However, for our sample of 625 early-type galaxies (ETGs) with integral-field spectroscopy from the SAMI Galaxy Survey, compared to correlations with mass, the color—gravitational potential ($\Phi$), [Z/H]--$\Phi$, and age—surface density ($\Sigma$) relations show both smaller scatter and less residual trend with galaxy size. These results lead us to the following inferences: (1) the color--$\Phi$ diagram is a more precise tool for determining the developmental stage of the stellar population than the conventional color--$M$ diagram; and (2) gravitational potential is the primary regulator of global stellar metallicity, via its relation to the gas escape velocity.
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Is the scatter in the star formation main sequence globally or locally driven?
With current observations constantly improving in resolution and probing increasingly smaller sub-galactic scales, it has been found that fundamental relationship between star formation rates and accumulated stellar mass persists across all scales. However, at what point do these measurements, and ultimately the Kennicutt-Schmidt law breakdown? Furthermore, do the physics of this relation emerge from such small local scales, or are they driven by large scale, global phenomena. Here we discover three distinct behaviours by individual galaxies in the spatially-resolved star formation main sequence and a critical scale at log(M*)~8.5 which divides behaviours that are locally vs. globally dominated. We suggest that these behaviours are likely constrained by their unique mass accretion histories, age, and galactic structure.
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With current observations constantly improving in resolution and probing increasingly smaller sub-galactic scales, it has been found that fundamental relationship between star formation rates and accumulated stellar mass persists across all scales. However, at what point do these measurements, and ultimately the Kennicutt-Schmidt law breakdown? Furthermore, do the physics of this relation emerge from such small local scales, or are they driven by large scale, global phenomena. Here we discover three distinct behaviours by individual galaxies in the spatially-resolved star formation main sequence and a critical scale at log(M*)~8.5 which divides behaviours that are locally vs. globally dominated. We suggest that these behaviours are likely constrained by their unique mass accretion histories, age, and galactic structure.
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Dissecting the mass-size relation: comparing half-mass radii across stellar mass, spectral type, and redshift
The mass-size relation and how it changes with redshift sheds light on how galaxies and their dark matter halos evolve. Galaxy sizes are typically measured from light profiles, but mass-to-light ratio gradients can cause half-mass and half-light radii to differ. Here, we present a new method for calculating the half-mass radii of distant galaxies. We calculate the half-mass radii of ~5,000 galaxies at 1<z<2.5 in the CANDELS footprint. The galaxies span a wide range of masses and star-formation rates, and allow us to investigate how galaxy sizes evolve over mass and redshift. Furthermore, we examine the physical origins of the galaxy mass-size relation by subdividing the blue and red galaxy populations into distinct subgroups based on their spectral shape.
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The mass-size relation and how it changes with redshift sheds light on how galaxies and their dark matter halos evolve. Galaxy sizes are typically measured from light profiles, but mass-to-light ratio gradients can cause half-mass and half-light radii to differ. Here, we present a new method for calculating the half-mass radii of distant galaxies. We calculate the half-mass radii of ~5,000 galaxies at 1<z<2.5 in the CANDELS footprint. The galaxies span a wide range of masses and star-formation rates, and allow us to investigate how galaxy sizes evolve over mass and redshift. Furthermore, we examine the physical origins of the galaxy mass-size relation by subdividing the blue and red galaxy populations into distinct subgroups based on their spectral shape.
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Star Formation Histories of $Z\sim1$ Galaxies in LEGA-C
Scaling relations between global galaxy properties and star-formation rate (SFR) activity suggest a close link between galaxy mass and dynamics on the one hand, and star-formation history (SFH) on the other. Due to the need for high-S/N, high-resolution continuum spectroscopy, reconstructing SFHs was previously only possible for local galaxies. The VLT LEGA-C Survey has collected high-quality spectra of $\sim3000$ galaxies at redshifts z\,$=0.6-1$, with the aim of revealing the internal dynamics and stellar population content of these galaxies. Based on reconstructed SFHs we show that: 1) the stellar ages of $z\sim1$ galaxies correlate strongly with their stellar velocity dispersions and ongoing SF activity; 2) the SFHs of L$_*$ galaxies with ongoing SF activity, unlike their present-day counterparts, are near their peak in SFR. By combining, for the first time, the lookback approach with the archaeological approach, these results illustrate the potential offered by high-S/N spectroscopy of high-redshift galaxies.
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Scaling relations between global galaxy properties and star-formation rate (SFR) activity suggest a close link between galaxy mass and dynamics on the one hand, and star-formation history (SFH) on the other. Due to the need for high-S/N, high-resolution continuum spectroscopy, reconstructing SFHs was previously only possible for local galaxies. The VLT LEGA-C Survey has collected high-quality spectra of $\sim3000$ galaxies at redshifts z\,$=0.6-1$, with the aim of revealing the internal dynamics and stellar population content of these galaxies. Based on reconstructed SFHs we show that: 1) the stellar ages of $z\sim1$ galaxies correlate strongly with their stellar velocity dispersions and ongoing SF activity; 2) the SFHs of L$_*$ galaxies with ongoing SF activity, unlike their present-day counterparts, are near their peak in SFR. By combining, for the first time, the lookback approach with the archaeological approach, these results illustrate the potential offered by high-S/N spectroscopy of high-redshift galaxies.
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Distribution of baryonic and dark matter in spiral and irregular nearby galaxies
Understanding the formation and evolution of galaxies requires a fine knowledge of the nowadays luminous and dark matter distribution within local galaxies. We present the mass distribution of a sample of 121 nearby galaxies with high quality optical velocity fields and available infra-red WISE 3.4µm data. These galaxies are part of the Fabry-Perot kinematical GHASP survey of spirals and irregular nearby galaxies. Combining the kinematical data to the WISE surface brightness data probing the emission from the old stellar population, we derive mass models allowing us to compare the luminous to the dark matter halo mass distribution in the optical regions of those galaxies. Dark matter (DM) models are constructed using the isothermal core profile and the Navarro-Frenk-White cuspy profile, as well as no-DM models following the MOND prescription. We allow the mass-to-light ratio of the baryonic disk to vary or we keep it fixed, constrained by stellar evolutionary models (WISE W1 - W2 colour) and we carry out best fit and pseudo-isothermal maximum disk models. For the DM models, the main results are: (i) the rotation curves of most galaxies are better fitted with core rather than cuspy profiles; (ii) the relation between the parameters of the dark matter and of the luminous matter components mostly depends on morphological types: e.g. different relations are found for bulgeless and bulgy systems.
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Understanding the formation and evolution of galaxies requires a fine knowledge of the nowadays luminous and dark matter distribution within local galaxies. We present the mass distribution of a sample of 121 nearby galaxies with high quality optical velocity fields and available infra-red WISE 3.4µm data. These galaxies are part of the Fabry-Perot kinematical GHASP survey of spirals and irregular nearby galaxies. Combining the kinematical data to the WISE surface brightness data probing the emission from the old stellar population, we derive mass models allowing us to compare the luminous to the dark matter halo mass distribution in the optical regions of those galaxies. Dark matter (DM) models are constructed using the isothermal core profile and the Navarro-Frenk-White cuspy profile, as well as no-DM models following the MOND prescription. We allow the mass-to-light ratio of the baryonic disk to vary or we keep it fixed, constrained by stellar evolutionary models (WISE W1 - W2 colour) and we carry out best fit and pseudo-isothermal maximum disk models. For the DM models, the main results are: (i) the rotation curves of most galaxies are better fitted with core rather than cuspy profiles; (ii) the relation between the parameters of the dark matter and of the luminous matter components mostly depends on morphological types: e.g. different relations are found for bulgeless and bulgy systems.
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Measuring the Scatter of the Radial Acceleration Relation
Of recent interest to galaxy formation studies are local scaling laws. One such local scaling law is the Radial Acceleration Relation (RAR) proposed by Lelli et al. (2017). Claiming that it is “One Law To Rule Them All”, Lelli et al. propose that the measured radial acceleration due to gravity follows that due to the baryonic mass tightly at all galaxy radii. So tightly, in fact, that the relation between them is consistent with zero intrinsic scatter. This RAR study was done with a galaxy sample of 175 selected spiral galaxies. I will present a RAR investigation which takes advantage of roughly 1000 spiral galaxies. While Lelli et al. have established the existence of the RAR, I am testing the zero intrinsic scatter claim. In this poster, I demonstrate the techniques used to extract the RAR for each galaxy and how the scatter is measured.
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Of recent interest to galaxy formation studies are local scaling laws. One such local scaling law is the Radial Acceleration Relation (RAR) proposed by Lelli et al. (2017). Claiming that it is “One Law To Rule Them All”, Lelli et al. propose that the measured radial acceleration due to gravity follows that due to the baryonic mass tightly at all galaxy radii. So tightly, in fact, that the relation between them is consistent with zero intrinsic scatter. This RAR study was done with a galaxy sample of 175 selected spiral galaxies. I will present a RAR investigation which takes advantage of roughly 1000 spiral galaxies. While Lelli et al. have established the existence of the RAR, I am testing the zero intrinsic scatter claim. In this poster, I demonstrate the techniques used to extract the RAR for each galaxy and how the scatter is measured.
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How to properly point your telescope to simulations
I will present the CosMoRIA simulations, a new suite of dwarf galaxy models that continue in the spirit of the MoRIA simulations (Verbeke+ 2015). I will show that to properly derive galaxy properties, it is crucial to follow the same techniques as observers do. When realistically "observing" our simulated galaxies, they follow a broad range of observed scaling relations. I will show the rotation curves of the CosMoRIA dwarfs, obtained using observational software (e.g. Gipsy or GalAPAGOS) and discuss the baryonic Tully-Fisher relation and the Radial Acceleration Relation (McGaugh+ 2016).
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I will present the CosMoRIA simulations, a new suite of dwarf galaxy models that continue in the spirit of the MoRIA simulations (Verbeke+ 2015). I will show that to properly derive galaxy properties, it is crucial to follow the same techniques as observers do. When realistically "observing" our simulated galaxies, they follow a broad range of observed scaling relations. I will show the rotation curves of the CosMoRIA dwarfs, obtained using observational software (e.g. Gipsy or GalAPAGOS) and discuss the baryonic Tully-Fisher relation and the Radial Acceleration Relation (McGaugh+ 2016).
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HI observations of Local Group dwarf irregulars with the SKA pathfinders.
We present high sensitivity, intermediate resolution Hi observations of Local Group dwarf irregular galaxies using the SKA pathfinders. The KAT-7 compact baselines and the MeerKAT core configuration make these instruments sensitive to large scale, low surface brightness emission, thus allowing us to probe far out into the dark halo potential and derive the large-scale kinematics of these galaxies. Dark matter components are presented using the pseudo-isothermal and Navarro-Frenk-White prescriptions. Our results suggest that dwarf irregular galaxies are better explained with core-like than cuspy dark matter components. Like most dwarf galaxies, the stellar disk does not contribute significantly to the rotation curve even in the inner regions. The critical densities for gravitational instabilities are calcu- lated using the Toomre-Q and cloud-growth based on shear criteria. We find that in regions of star formation, the cloud growth criteria based on shear explains better the star formation in dwarf irregular galaxies.
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We present high sensitivity, intermediate resolution Hi observations of Local Group dwarf irregular galaxies using the SKA pathfinders. The KAT-7 compact baselines and the MeerKAT core configuration make these instruments sensitive to large scale, low surface brightness emission, thus allowing us to probe far out into the dark halo potential and derive the large-scale kinematics of these galaxies. Dark matter components are presented using the pseudo-isothermal and Navarro-Frenk-White prescriptions. Our results suggest that dwarf irregular galaxies are better explained with core-like than cuspy dark matter components. Like most dwarf galaxies, the stellar disk does not contribute significantly to the rotation curve even in the inner regions. The critical densities for gravitational instabilities are calcu- lated using the Toomre-Q and cloud-growth based on shear criteria. We find that in regions of star formation, the cloud growth criteria based on shear explains better the star formation in dwarf irregular galaxies.
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Studies of the local dark matter velocity distribution using new cosmological simulations
The annihilation signal of dark matter (DM) relies significantly on its local velocity distribution. An accurate model of the local DM velocity distribution is essential to obtain reliable constraints on DM particle properties, currently a simple Gaussian distribution is used. We investigate the local DM velocity distribution using Milky Way mass-like galaxies generated from new, high-resolution, hydrodynamical cosmological simulations. Accounting for the effects of baryon physics, alignment of the galactic disk and the seasonal velocity variation. We define the local region over a radial distance of 8.5±1 kpc and up to 1 kpc from the galactic plane. Results show the velocity distribution in the local neighbourhood is not a simple Gaussian. We are investigating the effects of the triaxial shape of the DM halo and of the recently disrupted substructures may have in the local neighbourhood. This work aims to improve the constraints for the direct detection of DM.
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The annihilation signal of dark matter (DM) relies significantly on its local velocity distribution. An accurate model of the local DM velocity distribution is essential to obtain reliable constraints on DM particle properties, currently a simple Gaussian distribution is used. We investigate the local DM velocity distribution using Milky Way mass-like galaxies generated from new, high-resolution, hydrodynamical cosmological simulations. Accounting for the effects of baryon physics, alignment of the galactic disk and the seasonal velocity variation. We define the local region over a radial distance of 8.5±1 kpc and up to 1 kpc from the galactic plane. Results show the velocity distribution in the local neighbourhood is not a simple Gaussian. We are investigating the effects of the triaxial shape of the DM halo and of the recently disrupted substructures may have in the local neighbourhood. This work aims to improve the constraints for the direct detection of DM.
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Predictably Missing Satellites: Subhalo Abundances in Milky Way-like Halos
On small scales there are discrepancies between the standard Cold Dark Matter (CDM) model and observations. The 'missing satellites problem' infamously describes the overabundance of subhalos from CDM simulations compared to the satellites observed in the Milky Way. There have been numerous proposed solutions to the discrepancy, however none account for the properties of the Milky Way. Motivated by recent studies that show that the Milky Way is more atypical than expected (eg. Licquia et al. 2015) we look at a novel perspective analyzing the Milky Way's host halo properties - concentration, spin, shape, and scale factor of the last major merger - and their correlation with subhalo abundances. We present an N-body investigation of the subhalo-host halo connection by comparing the Mao et al. 2015 zoom-in simulations of Milky Way-mass halos to Milky Way data, concluding that even in dark matter simulations of the same mass the Milky Way is at the edge of host halo property distributions. From our data we determine that host halo properties are indicative of subhalo abundances for at least low mass subhalos. From our simulations and the measured properties of the Milky Way dark matter halo we build a model of Milky Way subhalo abundance based on its halo properties, and conclude that there should be at least 25-40\% fewer subhalos than have previously been predicted for the Milky Way.
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On small scales there are discrepancies between the standard Cold Dark Matter (CDM) model and observations. The 'missing satellites problem' infamously describes the overabundance of subhalos from CDM simulations compared to the satellites observed in the Milky Way. There have been numerous proposed solutions to the discrepancy, however none account for the properties of the Milky Way. Motivated by recent studies that show that the Milky Way is more atypical than expected (eg. Licquia et al. 2015) we look at a novel perspective analyzing the Milky Way's host halo properties - concentration, spin, shape, and scale factor of the last major merger - and their correlation with subhalo abundances. We present an N-body investigation of the subhalo-host halo connection by comparing the Mao et al. 2015 zoom-in simulations of Milky Way-mass halos to Milky Way data, concluding that even in dark matter simulations of the same mass the Milky Way is at the edge of host halo property distributions. From our data we determine that host halo properties are indicative of subhalo abundances for at least low mass subhalos. From our simulations and the measured properties of the Milky Way dark matter halo we build a model of Milky Way subhalo abundance based on its halo properties, and conclude that there should be at least 25-40\% fewer subhalos than have previously been predicted for the Milky Way.
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Environment- versus Mass-driven Quenching: Tracing Galaxy Evolution on Different Scales in the NUVrK diagram
The fact that galaxies can be classified according to their star-formation activity between "star-forming" and "quiescent" populations is now well established and this bimodality, clearly observed to redshift z~4, is the statistical expression of a (rapid) phenomenon called “quenching”. The process that is involved in the quenching of low-mass galaxies may, however, be quite different from what is involved in the quenching of massive galaxies after billion years of star formation on the Main sequence. I will discuss the existence of two quenching channels that can be identified in the NUVrK rest-frame colour diagram: one slow quenching channel followed by fairly massive galaxies, typically when reaching stellar masses of logM* ~10.64 M?, consistent with mass quenching within dark-matter halos of logMh ~12 M?, and a fast quenching channel required to explain the presence of low-mass quiescent galaxies, which we recently found to be consistent with environmental quenching of satellite galaxies.
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The fact that galaxies can be classified according to their star-formation activity between "star-forming" and "quiescent" populations is now well established and this bimodality, clearly observed to redshift z~4, is the statistical expression of a (rapid) phenomenon called “quenching”. The process that is involved in the quenching of low-mass galaxies may, however, be quite different from what is involved in the quenching of massive galaxies after billion years of star formation on the Main sequence. I will discuss the existence of two quenching channels that can be identified in the NUVrK rest-frame colour diagram: one slow quenching channel followed by fairly massive galaxies, typically when reaching stellar masses of logM* ~10.64 M?, consistent with mass quenching within dark-matter halos of logMh ~12 M?, and a fast quenching channel required to explain the presence of low-mass quiescent galaxies, which we recently found to be consistent with environmental quenching of satellite galaxies.
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Size evolution of the most massive galaxies since z~3
Galaxy size is an observational property which has been found to vary with galaxy mass, color and redshift and a physical property that reflects the evolutionary history of galaxies and their relationship with their dark matter halos. We present results on the size evolution of the most massive galaxies, with log(Mstar)>11.3, from the new COSMOS-Drift And SHift (DASH) survey. COSMOS-DASH provides 0.6 square degrees of HST/WFC3 F160W imaging in the COSMOS field. Separating the galaxies into star-forming and quiescent galaxies using their UVJ color, we find no statistical difference between their median sizes at z>2. The star-forming galaxies have a more rapid evolution with lookback time than quiescent galaxies, which is opposite to the effect observed in intermediate mass galaxies. We also find that at z>2.0 most massive galaxies are forming stars even though their inferred velocity dispersion are above the quenching threshold.
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Galaxy size is an observational property which has been found to vary with galaxy mass, color and redshift and a physical property that reflects the evolutionary history of galaxies and their relationship with their dark matter halos. We present results on the size evolution of the most massive galaxies, with log(Mstar)>11.3, from the new COSMOS-Drift And SHift (DASH) survey. COSMOS-DASH provides 0.6 square degrees of HST/WFC3 F160W imaging in the COSMOS field. Separating the galaxies into star-forming and quiescent galaxies using their UVJ color, we find no statistical difference between their median sizes at z>2. The star-forming galaxies have a more rapid evolution with lookback time than quiescent galaxies, which is opposite to the effect observed in intermediate mass galaxies. We also find that at z>2.0 most massive galaxies are forming stars even though their inferred velocity dispersion are above the quenching threshold.
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Effects of Galaxy Interactions on SFR and AGN Activity out to z ~ 2.8
Interacting galaxies may not follow galaxy scaling relations for a relatively short time-scale. Galaxy interactions act as perturbations to the galaxy system, providing an opportunity to study galaxy evolution under slightly different conditions. By probing the response of the system to these perturbations, i.e. by comparing the evolution of interacting galaxies with that of the non-interacting galaxies, i.e. by quantifying the effects of galaxy interactions, their correlations with one another, their time-scale/merger-stage and redshift dependence, we can have a deeper understanding of the processes taking place during the galaxy evolution. I will present the enhancement in AGN activity and SFR due to galaxy interactions for the largest known sample of spectroscopically confirmed galaxy pairs at 0 < z < 2.8 by using deep multiwavelength observations from the COSMOS and the CANDELS surveys. I will also present how enhancements depend on redshift and relative masses of the galaxies.
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Interacting galaxies may not follow galaxy scaling relations for a relatively short time-scale. Galaxy interactions act as perturbations to the galaxy system, providing an opportunity to study galaxy evolution under slightly different conditions. By probing the response of the system to these perturbations, i.e. by comparing the evolution of interacting galaxies with that of the non-interacting galaxies, i.e. by quantifying the effects of galaxy interactions, their correlations with one another, their time-scale/merger-stage and redshift dependence, we can have a deeper understanding of the processes taking place during the galaxy evolution. I will present the enhancement in AGN activity and SFR due to galaxy interactions for the largest known sample of spectroscopically confirmed galaxy pairs at 0 < z < 2.8 by using deep multiwavelength observations from the COSMOS and the CANDELS surveys. I will also present how enhancements depend on redshift and relative masses of the galaxies.
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The dust effects on galaxy scaling relations
Accurate galaxy scaling relations are essential for a successful model of galaxy formation and evolution as they provide direct information about the physical mechanisms of galaxy assembly over cosmic time. We present here a detailed analysis of a sample of nearby spiral galaxies taken from the KINGFISH survey. The photometric parameters of the morphological components are obtained from bulge-disk decompositions using GALFIT data analysis algorithm, with surface photometry of the sample performed beforehand. The method and the library of numerical results previously obtained in Pastrav et al. (2013a,b) are used to correct the measured photometric parameters for inclination, dust and decomposition effects in order to derive their intrinsic values. Galaxy scaling relations are then presented with and without corrections for these effects, at various wavelengths and specific dust opacities. While our sample is rather small, it is sufficient to emphasize the influence of galaxy environment (dust, in this case) when deriving scaling relations.
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Accurate galaxy scaling relations are essential for a successful model of galaxy formation and evolution as they provide direct information about the physical mechanisms of galaxy assembly over cosmic time. We present here a detailed analysis of a sample of nearby spiral galaxies taken from the KINGFISH survey. The photometric parameters of the morphological components are obtained from bulge-disk decompositions using GALFIT data analysis algorithm, with surface photometry of the sample performed beforehand. The method and the library of numerical results previously obtained in Pastrav et al. (2013a,b) are used to correct the measured photometric parameters for inclination, dust and decomposition effects in order to derive their intrinsic values. Galaxy scaling relations are then presented with and without corrections for these effects, at various wavelengths and specific dust opacities. While our sample is rather small, it is sufficient to emphasize the influence of galaxy environment (dust, in this case) when deriving scaling relations.
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Stellar Population Properties and Dynamical Modelling of Early-Type Galaxies with MUSE
The initial mass function has recently been discovered to vary systematically between, and also within, galaxies. However at this point, it is not obvious what galaxy property (or properties) the IMF normalisation scales with. We utilise high quality, spatially-resolved MUSE spectroscopy of three nearby early-type galaxies, allowing us to compare the IMF normalisation derived from both stellar population and dynamical modelling approaches, for galaxies spanning a range of velocity dispersion. I will present the results of our stellar population and dynamical modelling analyses, with a particular focus on how the IMF varies as a function of both global and local properties, and what constraints we can place on dark matter within these galaxies.
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The initial mass function has recently been discovered to vary systematically between, and also within, galaxies. However at this point, it is not obvious what galaxy property (or properties) the IMF normalisation scales with. We utilise high quality, spatially-resolved MUSE spectroscopy of three nearby early-type galaxies, allowing us to compare the IMF normalisation derived from both stellar population and dynamical modelling approaches, for galaxies spanning a range of velocity dispersion. I will present the results of our stellar population and dynamical modelling analyses, with a particular focus on how the IMF varies as a function of both global and local properties, and what constraints we can place on dark matter within these galaxies.
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Constraints on the low mass end of the Stellar Mass to Halo Mass scaling relation
The Stellar Mass to Halo Mass (SMHM) scaling relation, derived assuming abundance matching, is well constrained for halos of masses > 10^11 solar masses. Below this mass, there is a significant uncertainty, largely due to the lack of observed low-mass galaxies. I will show that the number of predicted dwarf galaxies in the Local Volume is drastically influenced by the various existing SMHM relations in the literature. I will then present our strategy for finding these low-mass field galaxies as part of the Dragonfly Wide-Field Survey and understand the dependence of their properties on the environment. We will use these data to empirically constrain the SMHM relation at the low mass end. Studying low-mass field galaxies, beyond our Local Group is essential for understanding the nature of low-mass dark matter halos (Danieli et al. 2016; Danieli, van Dokkum and Conroy et al. 2017).
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The Stellar Mass to Halo Mass (SMHM) scaling relation, derived assuming abundance matching, is well constrained for halos of masses > 10^11 solar masses. Below this mass, there is a significant uncertainty, largely due to the lack of observed low-mass galaxies. I will show that the number of predicted dwarf galaxies in the Local Volume is drastically influenced by the various existing SMHM relations in the literature. I will then present our strategy for finding these low-mass field galaxies as part of the Dragonfly Wide-Field Survey and understand the dependence of their properties on the environment. We will use these data to empirically constrain the SMHM relation at the low mass end. Studying low-mass field galaxies, beyond our Local Group is essential for understanding the nature of low-mass dark matter halos (Danieli et al. 2016; Danieli, van Dokkum and Conroy et al. 2017).
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Clues on the evolution of massive galaxies from the mass - size diagram
The dominant formation process of massive galaxies can be pinpointed by investigating how stellar kinematics and the black hole mass (Mbh) vary as a function of the host galaxy stellar mass and size. I will show the evidence for a change in Mbh above a critical galaxy mass. Next to the dependence on the velocity dispersion, Mbh in massive galaxies depends also on the galaxy stellar mass, which I will argue is an outcome of a sequence of dissipation-less mergers. Drawing on the results of the M3G survey, a campaign to observe massive galaxies with MUSE, I will present a bimodal distribution of kinematic misalignments for galaxies more massive than 10e12 Msun, with prolate-like rotation incidence of almost 50%. The change in the stellar kinematics of galaxies on the mass - size diagram reflects the change of the Mbh dependence, supporting dissipation-less major mergers as the dominant channel of massive galaxy formation.
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The dominant formation process of massive galaxies can be pinpointed by investigating how stellar kinematics and the black hole mass (Mbh) vary as a function of the host galaxy stellar mass and size. I will show the evidence for a change in Mbh above a critical galaxy mass. Next to the dependence on the velocity dispersion, Mbh in massive galaxies depends also on the galaxy stellar mass, which I will argue is an outcome of a sequence of dissipation-less mergers. Drawing on the results of the M3G survey, a campaign to observe massive galaxies with MUSE, I will present a bimodal distribution of kinematic misalignments for galaxies more massive than 10e12 Msun, with prolate-like rotation incidence of almost 50%. The change in the stellar kinematics of galaxies on the mass - size diagram reflects the change of the Mbh dependence, supporting dissipation-less major mergers as the dominant channel of massive galaxy formation.
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Supermassive black holes as the regulators of star formation in central galaxies
We present a relationship between the black hole (BH) mass, stellar mass, and star formation rate (SFR) of a diverse group of 91 local galaxies with dynamically-measured BH masses. We find that the specific SFR is a smoothly decreasing function of the BH-stellar mass ratio. We propose a physical framework where the amount of heating from low-accretion rate BH feedback suppresses a certain amount of cooling onto the galaxy and results in a corresponding SFR. Our results present a powerful diagnostic with which to test various prescriptions of BH feedback in models. Using the new IllustrisTNG simulation, we compare our observational results with simulation data to test our physical framework. In addition, we use dozens of other TNG runs with varying physics implementations to show how observable galaxy trends and correlations are affected by changes in BH feedback physics, thereby providing a pathway to physically interpret observations.
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We present a relationship between the black hole (BH) mass, stellar mass, and star formation rate (SFR) of a diverse group of 91 local galaxies with dynamically-measured BH masses. We find that the specific SFR is a smoothly decreasing function of the BH-stellar mass ratio. We propose a physical framework where the amount of heating from low-accretion rate BH feedback suppresses a certain amount of cooling onto the galaxy and results in a corresponding SFR. Our results present a powerful diagnostic with which to test various prescriptions of BH feedback in models. Using the new IllustrisTNG simulation, we compare our observational results with simulation data to test our physical framework. In addition, we use dozens of other TNG runs with varying physics implementations to show how observable galaxy trends and correlations are affected by changes in BH feedback physics, thereby providing a pathway to physically interpret observations.
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Connecting local and global galaxy-halo scaling relations via spatially resolved semi-empirical models
Traditional abundance matching derives empirical relationships between global galaxy properties (such as stellar mass) and halo properties (such as virial mass). This technique has recently been extended (e.g., Somerville et al. 2018) to derive constraints on galaxy structural properties (such as radial size) using halo structural properties (such as spin or concentration). In this talk, I will describe a novel further extension that we term "spatially resolved" abundance matching. Here, we make use of structural abundance matching to predict stellar mass profiles, and combine these with empirical spatially resolved scaling relations between stellar mass surface density, star formation rate surface density, cold gas mass surface density, gas metallicity, and rotation velocity. We then use the predicted distributions of structural properties for cosmological populations of halos from large-volume N-body simulations to explore what these local scaling relations imply for global galaxy scaling relations and their evolution.
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Traditional abundance matching derives empirical relationships between global galaxy properties (such as stellar mass) and halo properties (such as virial mass). This technique has recently been extended (e.g., Somerville et al. 2018) to derive constraints on galaxy structural properties (such as radial size) using halo structural properties (such as spin or concentration). In this talk, I will describe a novel further extension that we term "spatially resolved" abundance matching. Here, we make use of structural abundance matching to predict stellar mass profiles, and combine these with empirical spatially resolved scaling relations between stellar mass surface density, star formation rate surface density, cold gas mass surface density, gas metallicity, and rotation velocity. We then use the predicted distributions of structural properties for cosmological populations of halos from large-volume N-body simulations to explore what these local scaling relations imply for global galaxy scaling relations and their evolution.
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