Studying the X-ray Properties and Evolution of Extragalactic Sources Using Deep Multiwavelength Surveys

When reflecting on astronomy, many people's thoughts are flooded with images of planets, stars, and the Milky Way galaxy: sources that make up the majority of the bright objects visible in the night sky. Using X-ray light, I am studying galaxies well outside the Milky Way, reaching 100,000 times further than the brightest, most distant stars that are visible with the human eye! These observations allow us to look at galaxies as they were well back into time, as far as 12 billion light years, practically to the theoretical beginning of the universe! This is possible by using Chandra, a space-borne X-ray telescope analogous to the more well-known Hubble Space Telescope that observes in visible light. The most distant X-ray sources are only detectable by keeping the shutters on Chandra's lenses open for extended periods of time, and in the case of the deepest observations that I use in my research, these observations are as long as 25 days. These X-ray observations have helped me study distant black holes a billion times larger than Earth's sun that are vigorously consuming their surroundings and other more representative galaxies that are actively forming stars. My research also attempts to measure the influence of hot (sometimes exceeding 10 million degrees) gas that is found in galaxies. In addition to these X-ray sources, there is a significant amount of faint X-ray light that has been observed by Chandra in the deepest observations. Using statistical tools, I am studying the distribution of this light to see if it is associated with large gaseous structures that are predicted to exist outside of galaxies, but have not yet been observed. These structures are expected to contain a significant fraction of the Universe's mass, and their presence have important implications for how the Universe has evolved.