My research is mainly focused on understanding how stars formed early in the history of the universe. I’m involved in several projects studying the gas and dust in galaxies both very distant and very nearby. You can read more about the papers I’ve been most heavily involved with here or the complete sample at Recent Projects.
Distant Dusty, Star-forming Galaxies
Designed to make large-scale maps of the variations in the Cosmic Microwave Background Radiation, the South Pole Telescope has mapped about 2500 square degrees of the southern sky at 1.4 – 3mm wavelengths. These maps uncovered a large number of bright sources, almost all of which correspond to nearby galaxies astronomers have known about for decades. Some of them, though, are very luminous, very distant galaxies forming new stars at incredible rates, and are almost all gravitationally lensed. Gravitational lensing magnifies the galaxies, allowing us to study them at otherwise-impossible resolution and study aspects which would otherwise be too faint to observe. With a team of collaborators, I’m taking advantage of the unique sample to understand what makes these very young galaxies able to form stars hundreds or thousands of times faster than our own Milky Way galaxy. You can read more about our recent work here.
Gas in Compact, Star-Forming Galaxies
When we look at nearby galaxies, we can divide them into two basic classes – spirals and ellipticals. Most spiral galaxies are forming new stars, while most ellipticals are not (astronomers call them “quiescent”). We first start to see large numbers of quiescent galaxies when the universe was about 20% of its current age, but these early quiescent galaxies are much, much smaller than the nearby elliptical galaxies we see today. I’m working on a project using the Very Large Array and NOEMA interferometer to study the gas in galaxies that look almost like the early quiescent galaxies (i.e., small and massive) but are still forming stars. This may allow us to determine if the star-forming galaxies are in the process of rapidly turning off their star formation to become quiescent.
Mapping the Large Magellanic Cloud
I’m also involved in a project to map the gas in a large portion of the Large Magellanic Cloud, a small satellite galaxy to our own Milky Way galaxy. The gas in the LMC hasn’t been as processed by stars as the gas in the Milky Way has, so it has fewer heavy elements (carbon, nitrogen, oxygen, etc.), making it a valuable laboratory to see how the process of star formation depends on the composition of the gas stars form out of. The LMC is close by, which means we can study it in great detail, but also means it’s very large on the sky, so mapping the entire thing is difficult. Using the Supercam 64-pixel receiver on the APEX telescope, we’re able to map a large portion of the galaxy quickly.