Postdoctoral Fellowship: AAPF: Mapping the Outskirts of Galaxies with the Dark Energy Spectroscopic Instrument

Nathan Sandford is awarded an NSF Astronomy and Astrophysics Fellowship to carry out a program of research and education at the University of California, Santa Cruz. Using observational data from the Dark Energy Spectroscopic Instrument (DESI), Sandford will study the outskirts of galaxies in the Local Group to gain insight into the nature of dark matter. The project will also recruit and train teams of UCSC graduate students in the design and teaching of inquiry-based investigations involving real astronomical data for community college students at Lick Observatory. Using stellar spectroscopy from the DESI-Ib Local Group dwarf galaxy program, Sandford will perform a comprehensive chemodynamic analysis of five dwarf galaxies - creating the largest sample of spectroscopically confirmed members in these galaxies out to 10 or 20 half-light radii. This work will enable the identification of extended stellar halos and tidal debris, the precise inference of dark matter density profiles, and the quantification of the effects of stellar feedback via stellar chemistry. These measurements will link the formation of extended stellar halos and tidal features to underlying dark matter and baryonic processes, providing both novel constraints and robust empirical benchmarks for cosmological simulations. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.