Compact Groups


One of NASA's big question's is "How do planets, stars, galaxies and cosmic structure come into being?" This is a question that, in some form, has fascinated humans for thousands of years. Initially, the question of where we came from only applied to humans, but as our understanding of the world around us has grown, so has the extent of this question. We used to believe that Earth was the center of the universe, but when we realized that Earth is actually one of several planets orbiting the sun, the question became where our solar system came from. When we discerned that our star was one of millions making up a galaxy, or "island universe," we began to wonder not only where it came from but how big it was. Eventually, we came to understand that our galaxy is part of a cosmic web of galaxies that make up the universe. We now know that everything around us, everything there is, started in one Big Bang. Now the question is how we got from the Big Bang to the world and universe we live in today. To understand this, we must understand the origin of cosmic structure. It is now thought that galaxies formed through "hierarchical formation," where galaxies grow by merging with similarly-sized galaxies and accreting smaller galaxies, and clusters formed when galaxies would gather in gravitational potential wells.


Compact groups of galaxies are a nearby environment with conditions similar to those in the early universe when galaxies were assembled. They provide an opportunity to witness hierarchical formation in progress. Our studies of compact groups aim to determine how this intense environment - one of high galaxy density and constant interactions - affects the evolution of the member galaxies. Our research with Spitzer Space Telescope has already found clear evidence that galaxies in compact groups evolve differently than galaxies in other environments, but it is not yet fully understood why. To understand the processes that cause these galaxies to evolve differently, we will now investigate one of the fundamental building blocks of galaxies: the cold gas. This will provide important insight into the interactions of these galaxies as well as their star formation. Without the presence of gas, galaxies cannot form.


Simulation of a compact group of galaxies by Joshua Barnes

Star Formation Group

I am a member of the star formation group at UVa. We study the physics of star formation from 100AU to 100kpc scales, from individual protostars in our Galaxy to compact groups of galaxies. This breadth allows us to ground galaxy-scale star formation in an understanding of the microphysics, and place individual nearby regions in broader environmental context. We use observational techniques from X-ray to centimeter, with particular recent focus on infrared and (sub)millimeter, as well as radiative transfer and other numerical models.

site info

© 2011-2013 Lisa May Walker. Design by Andreas Viklund.