John Kormendy is the Curtis T. Vaughan, Jr. Centennial Chair in Astronomy Emeritus at the University of Texas at Austin. He held the Chair Professorship from 2000 to August 2017. Before that, he was Professor of Astronomy at the University of Hawaii at Manoa from 1990 through 1999 and a Staff Member at the Dominion Astrophysical Observatory in Victoria, Canada, from 1980 through 1989. Kormendy received his BSc degree from the University of Toronto, Canada, in 1970 and his PhD from the California Institute of Technology in 1976. He was Parisot Postdoctoral Fellow in the Berkeley Astronomy Department of the University of California in 1976 – 1978 and held a Postdoc at Kitt Peak National Observatory from 1978 – 1980. He also was a Senior Visiting Fellow at the Institute of Astronomy, University of Cambridge, UK for several months in 1978 and 1980.
Kormendy is an observer with a background in theoretical dynamics. His research concentrates on galaxy structure and evolution. His technical expertise is in optical and near-infrared photometry and medium-resolution spectroscopy to measure the structure and dynamics of stars, gas, and (indirectly) dark matter in galaxies, including supermassive black holes in galaxy centers and cosmological dark matter in galaxy halos. Kormendy's research concentrates on six areas:
1: Structure and evolution of elliptical galaxies and those (“classical”) bulges of disk galaxies that are observationally indistinguishable from ellipticals. Both are thought to be products of galaxy collisions and mergers that scramble progenitor disks into ellipsoidal remnants. Kormendy’s PhD thesis derived one of the fundamental structural scaling laws to be explained by theories of galaxy formation, the “Kormendy relation” between the effective radius and effective brightness of classical bulges and ellipticals. An extensive 2009 study of essentially all Virgo Cluster ellipticals further “nailed” the developing result that elliptical galaxies come in two varieties, (1) coreless ellipticals with disky isophote distortions and rapid rotation that are believed to be products of dissipative mergers with starbursts and (2) giant ellipticals with “excavated” cores, boxy distortions, and slow rotation that are thought to be remnants of dissipationless mergers – ones in which progenitor and remnant mass are large enough to hold onto X-ray-emitting, hot gas that quenches star formation. Absent gas dissipation and star formation, black hole binaries that are made in mergers can excavate “cores” by flinging stars away from the center. Support for this idea comes from observed, very tight correlations between core properties and black hole masses.
2: Structure and evolution of galaxy disks: The problem is that, in a Universe dominated by the hierarchical clustering and merging of galaxy fragments, we do not have a robust understanding of how to form pure disks, i. e., ones that lack classical bulges. Pure disks dominate field environments.
3: Internal “secular evolution” of disk galaxies: Secular evolution is slow – it happens on time scales of many galaxy rotations. Disks evolve secularly when nonaxisymmetries such as bars rearrange the angular momentum distributions of stars and gas. One product of this evolution is “fake bulges” or “pseudobulges” that, in the past, were frequently confused with elliptical-galaxy-like classical bulges but that are grown slowly out of disks, not made rapidly via mergers. Kormendy was the first person to emphasize the importance of these processes (1979), and they are still one of his most active research areas (e. g., an Annual Review of Astronomy and Astrophysics review with Rob Kennicutt in 2004). An important consequence is that we now recognize that supermassive black holes do not correlate with pseudobulges – or, indeed, with disks and dark matter halos – tightly enough to imply coevolution (Kormendy & Ho 2013, ARA&A, 51, 511).
4: Environmental secular evolution: Disk galaxies that live in clusters of galaxies and in other dense environments get transformed by a variety of (mostly slow) processes that remove gas and change them into a newly recognized type of galaxy called a “spheroidal” (Sph). In the past, spheroidals were confused with ellipticals. Kormendy has, for most of his career, emphasized that spheroidals are not small ellipticals; rather, they are continuous in their scaling relations with S0 disks. That is, Sph galaxies are, in essence, S0 galaxies that have no bulge components. Together, S0 disks and Sph galaxies have the same scaling relations as spiral galaxy disks and Magellanic irregular (Im) galaxies. The suggestion is that they are “red and dead” versions of S+Im galaxies, transformed by internal and environmental processes that remove cold gas and kill star formation.
5: Supermassive black holes in galaxy centers: The search for black holes via spatially resolved stellar dynamics and the study of black hole demographics has been one of Kormendy's most important research areas since the late 1980s. He used the Canada-France-Hawaii Telescope on Mauna Kea, Hawaii to find 3 of the first 4 dynamically-discovered supermassive black holes in galaxies. All are confirmed with the Hubble Space Telescope (HST); care with the early part of this work helped to establish this subject. Kormendy was the first to define and illustrate the correlation between black hole mass and the luminosity (hence also stellar mass) of the host bulge component. As a member of the “Nuker Team” that used HST to search for black holes, he was co-discoverer of the correlation between black hole mass and the velocity dispersions of stars in the host bulge. Nuker team work also discovered more than a dozen new black hole candidates. And Nuker team work showed that the pure-disk galaxy M33 does not contain a supermassive black hole. This was an early sign of the now-well-established result that black hole masses do not correlate with the properties of galaxy disks. Black hole demographics and scaling relations were reviewed and updated, including black hole mass corrections that revealed many new results, in Kormendy & Ho 2013, ARA&A, 51, 511.
6: Scaling laws for cosmological dark matter halos were discovered in Kormendy's work in the 1980s. They were derived in detail in Kormendy & Freeman 2016, ApJ, 817, 84. An important result of this work is the recognition that baryons become dynamically unimportant in galaxies not when the dark matter halo mass MDM → 0 but rather in halos in which the outer circular-orbit rotation velocity is 42 ± 4 km/s. Smaller galaxies are dim or dark. Dark dwarfs are predicted by our picture of cold dark matter galaxy formation.
Kormendy has been awarded the Gold Medal of the Royal Astronomical Society of Canada (1970), the Muhlmann Prize of the Astronomical Society of the Pacific (1988), a Humboldt Research Award of the Alexander von Humboldt Foundation, Germany (2006), and External Membership in the Max-Planck-Insitute for Extraterrestrial Physics in Garching-by-Munich, Germany (2012). He was an Associate Editor of Annual Review of Astronomy and Astrophysics from 2004 – 2014.