Jelena Aleksić: Eight New Milky Way Companions Discovered in First-Year Dark Energy Survey Data

Wednesday 11 Mar 2015, 13:00 → 14:00 Europe/Madrid

Seminar (IFAE)

Jelena Aleksic (IFAE), Joern Lange (IFAE Barcelona), Stefania Bordoni (IFAE)

I report on the discovery of eight new Milky Way companions in ~1,800 deg^2 of optical imaging data collected during the first year of the Dark Energy Survey (DES). Each system is identified as a statistically significant over-density of individual stars consistent with the expected isochrone and luminosity function of an old and metal-poor stellar population. The objects span a wide range of absolute magnitudes (M_V from -2.2 mag to -7.4 mag), physical sizes (10 pc to 170 pc), and heliocentric distances (30 kpc to 330 kpc). Based on the low surface brightnesses, large physical sizes, and/or large Galactocentric distances of these objects, several are likely to be new ultra-faint satellite galaxies of the Milky Way and/or Magellanic Clouds. I also present the results of search for gamma-ray emission coincident with the positions of these new objects in six years of Fermi Large Area Telescope data. Also shown are the expectations on the velocity-averaged dark matter annihilation cross section for these new targets, assuming that they indeed are dwarf satellites with dark matter halo properties similar to those of the known dSph population.