Balancing Gas Loss, Star Formation, and Black Hole Activity in Cluster Galaxies

Vijayaraghavan Rukmani, Urbana IL

Investigators

Abstract

Rukmani Vijayaraghavan is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to carry out a program of research and education at the University of Virginia. Galaxies in dense groups and clusters, unlike ordinary field galaxies like the Milky Way, are subject to extreme astrophysical processes that remove their gas and shut down star formation. These processes are far from gentle; many galaxies go through a violent evolutionary phase before settling into their eventual passive gas-poor states. During this phase, star formation and supermassive black hole activity within galaxies can be triggered by strong pressure in the ambient gas. Energy injected by these stars and supermassive black holes can in turn replenish gas lost from galaxies, further continuing this cycle. These processes, mysteriously, operate in the presence of other mechanisms in dense environments that should destroy galactic gas. While there is abundant observational evidence that these processes operate in cluster galaxies, a theoretical understanding of the physics driving the energy cycle in group and cluster galaxies remains elusive. Vijayaraghavan will exploit recent advances in computing and astrophysical software development to carry out a simulations-based investigation into these extreme astrophysical phenomena. She will also run an educational program to promote enthusiasm for computational astrophysics in middle-school-aged girl students. These students will be exposed to the latest scientific developments and techniques in modern astrophysics through computer- and telescope-based activities. Solving the problem of galaxy evolution in cluster environments requires modeling and disentangling the contribution of multiple simultaneous complex physical phenomena, operating over six orders of magnitude in physical scale. Vijayaraghavan will perform a series of supercomputer simulations using the FLASH code to progressively incorporate multiple physics modules, and use adaptive mesh refinement to focus computational resources on interesting regions. In these simulations, cosmologically realistic red and blue galaxies, including their stellar and gas components, will be allowed to evolve within massive group and cluster environments in the presence of progressively complex physical processes. Based on these simulations, Vijayaraghavan will identify and disentangle the physical mechanisms triggering star formation and black hole activity in cluster galaxies, and investigate the impacts of these processes on cluster galaxy evolution. She will also generate mock observations from simulations to directly compare with radio, optical, and X-ray observations of the hot and cold gas, star formation, and black hole activity in cluster galaxies. This project will use supercomputing resources at the University of Virginia and NSF XSEDE supercomputers. The educational component of this program will be based around summer day camps, where girls will gain an understanding of modern astrophysics through a combination of interactive presentations and hands-on experience with computers and observatory telescopes. The object of these camps will be to inspire girls to pursue careers in STEM fields.