Professor of Physics
Research InterestsGalaxy Evolution, Intergalactic Medium, and Experimental Astrophysics
I would like to understand the history of star formation in galaxies and the physical conditions that govern this history. I am particularly interested in how the baryonic gas that begins as the intergalactic medium (IGM) ultimately finds its way into galaxies and stars, and how those galaxies feedback energy and material into that natal gas. In order to do this we are exploiting various observational tools to study star formation history. I am the Principal Investigator of the Galaxy Evolution Explorer (GALEX), a NASA satellite mapping the sky in the UV. The ultraviolet provides one of the most sensitive ways to detect the low levels of star formation that occur in the outskirts of galaxies, in low mass systems, in galaxies that are shutting down their star formation, and in young galaxies with few heavy elements. Many of our GALEX studies require follow-up observations with Palomar, Keck, HST, and other facilities. Measuring star formation laws and history in these diverse physical environments will help to construct a theory of baryonic structure formation, but new and challenging observations are also needed.
We are therefore pursuing several new experimental programs to detect and map emission from the intergalactic medium. These maps could delineate the baryonic reservoirs of gas that fuel on-going galaxy formation and evolution over time, reveal the direct impact of galactic feedback on the surrounding medium, and provide a new cosmological tool. In space, we are currently flying a balloon UV integral field spectrograph (FIREBALL) designed to detect and map IGM emission at z~0.7. This is a prototype of a satellite experiment that would detect and map IGM emission over the 0<z<1.5 redshift range. From the ground, we are constructing the Cosmic Web Imager for the Hale telescope, and the Keck Cosmic Web Imager. These will detect and map IGM emission from redshift 2 to the reionization redshift of z~6-7. All of these experiments can be used to make many other new and path-breaking measurements.
Our projects are perfect for graduate student mentoring and leadership. We are seeking students who are interested in combining experience building new instruments with frontier science observations.
Credit: NASA/JPL-Caltech/C. Martin (Caltech)/M. Seibert (OCIW)
[Image credits: Bob Paz; NASA/JPL-Caltech/C. Martin (Caltech)/M. Seibert (OCIW)]