When a supermassive black hole in the center of a galaxy is voraciously consuming its surrounding material, it can become very bright for approximately 100 Myr until it somehow turns itself off or runs out of fuel. During this stage, we call the supermassive black hole a quasar. Quasars are some of the most luminous objects in the universe, yet we know understand very little about how they actually form or interact with their environment. One popular theory is that quasars are turned on through violent galaxy-galaxy collisions.




Our work on this topic has included studying quasars in interacting galaxies to understand how the quasars may have formed and learn more about how they affect their environment. Most spectacularly, we have studied an interacting pair of galaxies where one galaxy has a quasar that appears to have photionized a tidal feature that extends for 40 kpc (130,000 lightyears)! This process allows us to study the gas in those galaxies in an entirely new way.

Currently we are working on using the giant Sloan Digital Sky Survey combined with simulations of galaxy mergers in order to statistically study the fraction of quasars that are triggered in a particular type of merger.

One of the most basic questions that humans have asked for generations is how do stars form. One of the more theoretically perplexing aspects of star formation is that, we know observationally that stars appear to form with a distinct distribution of masses which appears to be roughly constant anywhere you look in the universe. People for decades have looked for regimes where this initial mass distribution of stars (known as the initial mass function or IMF) varies systematically as a function of a given parameter.

Recently, some have proposed the this distribution varies for regions with very small amounts of star formation. However, in this regime there are statistical stochastic fluctuations that can mimic the effects of a varying IMF. These effects are complicated by the fact that stars form in clusters. Previously, there had been no tool which fully took into account these stochastic processes coupled with the clustering of stars so we decided to develop our own (called SLUG because it Stochastically Lights Up Galaxies).

While this tool was conceived to address this particular problem, it has a wide range of other applications. Its particular implementation of star formation appears to agree with observations very well and has implications for how we think about star formation on a basic level.

Galaxies are made up of stars. Those stars are formed out of gas that the galaxy has accreted over time. Through various violent processes such as supernovae and massive stellar winds, those stars can drive large outflows of gas out of their galaxies. These outflows are rich in metals which pollute their surrounding vicinity. Understanding these outflows is crucial for understanding how galaxies obtain and lose their gas which ultimate determines how they form stars. They also are crucial for understanding how metals get distributed throughout the universe.

We study these galactic outflows with data obtained in one of the largest high redshift galaxy surveys ever performed: the DEEP Survey. Using a new technique we are able to study and characterize these outflows better than any previous study.