A Gaia DR2 search for dwarf galaxies towards Fermi-LAT sources: implications for annihilating dark matter

Understand

We make a first attempt to find dwarf galaxies in eight \Fermi-LAT extended, unassociated, source fields using \Gaia\ DR2.

• We probe previously unexplored heliocentric distances of $d<20$~kpc with an extreme-deconvolution (XD) technique.
• We find no signature of a dwarf galaxy in any of these fields despite \Gaia's excellent astrometric accuracy.
• We estimate our detection limits by applying the XD method to mock data, obtaining a conservative limit on the stellar mass of $M_* < 10^4$~M$_{\sun}$ for $d < 20$\, kpc.