Professor Wittman has discovered millions of galaxies as co-PI of the Deep Lens Survey, which was awarded over 100 nights on 4-m telescopes to study a representative sample of the universe. But discovering millions of galaxies was the easy part. He analyzed the galaxies' shapes to reveal subtle distortions caused by the gravitational fields of foreground masses, an effect called weak gravitational lensing. He was the first to detect cosmic shear, or weak lensing by the large-scale structure of the universe. He was also the first to detect a cluster of galaxies through its gravitational effects alone, and the first to combine source redshift information with lensing to probe structure in three dimensions (tomography). Because most matter is dark, these observations constrain the density of dark matter in the universe.
Professor Wittman's recent work focuses on clusters of galaxies that
collide, revealing interactions between gas, galaxies, and dark matter.
These collisions play out over hundreds of millions of years but we observe
just a snapshot in our lifetimes. Wittman's group observes these systems
with spectroscopy and gravitational lensing, and creates models of the
entire process based on snapshots of different systems observed at
different stages of the process. The goal of this modeling is to determine
whether dark matter interacts nongravitationally, which is an important
question for particle models of dark matter. Wittman is also developing
novel methods of gravitational lensing to enable more precise lensing
observations of these systems.
- Ph.D., University of Arizona, 1997
- Technical Staff at Bell Laboratories, Lucent Technologies from 1997-2004
- Assistant Research Physicist, University of California, Davis, May, 2004
- Assistant Professor, University of California, Davis, 2006
- Fulbright Scholar, 2015
- SPIE Scholarship in Optical Engineering, 1993