More than 80 percent of the mass of the universe consists of a mysterious non-luminous material known as dark matter. After factoring in another enigma, the repulsive force called dark energy that dominates the universe's expansion, astronomers have a detailed understanding of only 5 percent of the contents of the universe.
Since the discovery in 2005 of the smallest galaxies known, the ultra-faint dwarfs, Simon and colleagues have used these extreme systems as laboratories for studying both dark matter and the evolutionary history of the first galaxies. They have demonstrated that the ultra-faint dwarfs are the oldest, most metal-poor, and most dark matter-dominated galaxies yet found, providing new insight into topics ranging from the search for the dark matter particle to the explosions of the first stars. In the course of this work, they also discovered extremely metal-poor stars in dwarf galaxies. This finding led Simon to begin a new survey using the Magellan telescopes to identify and study the chemical abundance patterns of a much larger sample of the lowest metallicity stars in nearby dwarfs. This effort will produce a statistically significant number of such stars beyond the Milky Way for the first time, enabling observational constraints on the yields of the first supernovae, the sites of production of the heaviest elements, and the formation of the stellar halo of our galaxy.
In addition to dark matter and metal-poor stars, Simon's interests span all aspects of galaxies in the nearby universe, including supernovae, chemical evolution, star formation, and the stellar initial mass function of the Milky Way's closest neighbors, as well as the search for new dwarf galaxies in the Local Group and beyond.
- Ph.D. in Astrophysics, 2005, University of California - Berkeley
- M.A. in Astrophysics, 2000, University of California - Berkeley
- B.S. in Physics, 1998, Stanford University