Center for Computational Astrophysics: Galaxy Formation

A fully predictive theory of galaxy formation remains one of the great, unsolved problems of astrophysics. Galaxy formation represents the intersection of many branches of physics from cosmology to plasma physics, and involves a vast range of length and timescales.  The Galaxy Formation group is developing the numerical tools and physical insights necessary to understand how galaxies form and evolve within a cosmological context.  Our goal is to explain a wide range of observations ranging from high redshift quasars down to the smallest local dwarf galaxies. Topics that group members are working on include:

  • understanding how massive stars and supernovae drive galaxy-wide winds
  • predicting how the universe became reionized and the nature of the first stars, galaxies, and black holes
  • simulating cosmic ray driven winds and exploring their importance in galaxy formation
  • developing numerical methods for hydrodynamics and magnetohydrodynamics
  • understanding how supermassive black holes accrete and grow, and how they affect their galactic hosts and surroundings
  • modeling multi-phase gas in, around, and between galaxies
  • applying advanced statistical tools to extract insights from cosmological simulations
  • developing tools to take galaxy simulations “to the observational plane”
Greg L. Bryan

Greg Bryan, Ph.D.

Galaxy Formation Group Leader, CCA

Greg L. Bryan is a professor of astronomy at Columbia University and a co-leader of the galaxy formation group at the Simons Center for Computational Astrophysics. He received a Ph.D. in astrophysics at the University of Illinois at Urbana-Champaign in 1996 and held positions at Princeton, MIT, and Oxford before joining the faculty at Columbia in 2004 and the Simons Foundation in 2016. He is a recipient of a Princeton Lyman Spitzer Fellowship, a Hubble Fellowship, an NSF CAREER award and the Leverhulme Trust Prize. His primary research focus involves the use of large-scale computational hydrodynamics and computational models to better understand astrophysical systems in a cosmological framework. He has applied such techniques to study the generation of large-scale structure in the universe, the formation of X-ray clusters, the evolution of galaxies and the birth of the first stars in universe. He has also carried out numerical simulations used to generate visualizations for the Oscar-nominated IMAX film Cosmic Voyage, as well as planetarium shows at the American Museum of Natural History.

Amanda Weltman

Amanda Weltman, Ph.D.

Consultant, Galaxy Formation

Amanda Weltman is an associate professor in the department of mathematics and applied mathematics at the University of Cape Town, a NRF/DST South African Research Chair in Physical Cosmology and a consultant in the galaxy formation group of CCA. Her research focuses on the fundamental physics that underlies the nature of the universe. The goals of her research are to study the universe as a whole, while gaining insight into its origin, composition, structure, evolution and ultimately its fate. Weltman has won several prestigious awards, including a Next Einstein Fellow award, the South African Institute of Physics Silver Jubilee Medal, the Elsevier Young Scientist Award and many others. She is a member of the Cape Town Science Centre Scientific Advisory Board, the South African Royal Society and on the executive of the South African Young Academy of Sciences. Weltman earned a B.S. in applied mathematics and physics at the University of Cape Town and a Ph.D. in physics from Columbia University. She then worked as a postdoctoral researcher at Cambridge University’s Center for Theoretical Cosmology before returning to the University of Cape Town.

Chris Hayward, Ph.D.

Associate Research Scientist, CCA

Chris Hayward joined the foundation in 2016 as an associate research scientist at the Center for Computational Astrophysics. He uses a variety of tools, ranging from analytic calculations to simulations to observations, to advance our understanding of how galaxies form. A particular emphasis of Hayward’s research is on combining hydrodynamic simulations of galaxy formation with radiative transfer calculations to create ‘forward models’ of observable quantities, such as images and spectra, that can be directly compared with data from telescopes such as the Hubble Space Telescope. Hayward earned his Ph.D. at Harvard University. Before joining the CCA, he was a postdoctoral scholar at the Heidelberg Institute for Theoretical Studies in Germany and a Moore Prize postdoctoral scholar in theoretical astrophysics at the California Institute of Technology.

Rachel Somerville, Ph.D.

Consultant, Galaxy Formation

Rachel Somerville is the George A. and Margaret M. Downsbrough Chair in astrophysics at Rutgers University and a consultant with the galaxy formation group of CCA. She co-leads the galaxy formation group, along with Greg Bryan. Somerville uses semi-analytic modeling, simulations and observations to probe the formation and evolution of galaxies, work that earned her the 2013 Dannie Heineman Prize for Astrophysics. The main goal of her research is to understand how galaxies and supermassive black holes form and evolve within a cosmological context. She has served on the faculty at the University of Michigan and headed the theory group at the Max Planck Institute for Astronomy in Heidelberg, Germany and was formerly a member of the science staff at the Space Telescope Science Institute and a research professor at Johns Hopkins University, both in Baltimore, Maryland. She received her Ph.D. from the University of California, Santa Cruz and did postdoctoral work at the Hebrew University in Jerusalem and the Institute of Astronomy at the University of Cambridge. She earned her bachelor’s degree in physics and music from Reed College in Portland, Oregon.

Shy Genel

Shy Genel, Ph.D.

Associate Research Scientist, CCA

Shy Genel joined the foundation in 2016 as an associate research scientist at the Center for Computational Astrophysics. His research interests lie in the field of galaxy formation, as well as in numerical methods. To study how galaxies evolve, Genel runs and analyzes large computer simulations that generate ‘mock universes’ and develops codes for these purposes. Since completing his Ph.D. at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, Genel has held several postdoctoral fellowships, including the Hubble fellowship at Columbia University and a fellowship at the Institute for Theory and Computation at Harvard University.

Lauren Anderson

Lauren Anderson, Ph.D.

Research Fellow, CCA

Lauren Anderson joined the foundation in 2016 as a postdoctoral fellow at the Center for Computational Astrophysics. She recently graduated from the University of Washington with a Ph.D. in Astronomy, and prior to that, she earned a B.A. in Physics and Astronomy from the University of California, Berkeley. She currently works on analyzing large cosmological simulations to understand the formation of galaxies in the early universe and the effect these galaxies had on their local environments. Her thesis work was on the contribution of little galaxies to reionization, an epoch in early cosmological history that is still not well understood.

Chia-Yu Hu, Ph.D.

Research Fellow, CCA

Chia-Yu Hu joined the foundation in 2016 as a research fellow at the Center for Computational Astrophysics. His research focuses on the physics of the interstellar medium and its connection to galaxy evolution. To this end, Chia-Yu develops accurate numerical methods and conducts high-resolution numerical simulations to follow the complex interplay between different physical processes at multiple scales. Before joining the foundation, Chia-Yu was a graduate student at the Max-Planck-Institute for Astrophysics in Garching, Germany, where he completed his Ph.D. in astrophysics. He holds an M.S. in astrophysics and a B.S. in materials engineering from National Taiwan University.

Elijah Visbal, Ph.D.

Research Fellow, CCA

Elijah (Eli) Visbal joined the foundation in 2016 as a research fellow at the Center for Computational Astrophysics. He has worked on a range of topics in theoretical astrophysics and cosmology, focusing recently on modeling the formation of the first stars and supermassive black holes within the first billion years after the Big Bang. Prior to joining the foundation, Visbal was a postdoctoral fellow at Columbia University. He holds a B.S. in physics from Carnegie Mellon University and a Ph.D. in physics from Harvard University.

Melanie Habouzit

Melanie Habouzit, Ph.D.

Flatiron Research Fellow, CCA

Melanie Habouzit joined the foundation in October 2016 as a Flatiron research fellow in the Center for Computational Astrophysics after completing her Ph.D. at the Institut d’Astrophysique de Paris. Her research interests lie in the field of galaxy formation and evolution, with a particular focus on supermassive black holes that reside at the center of galaxies. Habouzit implements, runs and analyzes large-scale cosmological hydrodynamical simulations to study the evolution of black holes and their host galaxies and to make theoretical predictions on the number of observable black holes in the universe.