Unidentified sources in the Fermi-LAT second source catalog: the case
  for DM subhalos
  The Large Area Telescope (LAT) aboard the Fermi satellite allows us to study
the high-energy gamma-ray sky with unprecedented sensitivity. However, the
origin of 31% of the detected gamma-ray sources remains unknown. This
population of unassociated gamma-ray sources may contain new object classes,
among them sources of photons from self-annihilating or decaying non-baryonic
dark matter. Fermi-LAT might be capable to detect up to a few of these dark
matter subhalos as faint and moderately extended gamma-ray sources with a
temporally steady high-energy emission. After applying corresponding selection
cuts to the second year Fermi catalog 2FGL, we investigate 13 candidate objects
in more detail including their multi-wavelength properties in the radio,
infrared, optical, UV, and X-ray bands. For the gamma-ray band, we analyze both
the 24-month and 42-month Fermi-LAT data sets. We probe the gamma-ray spectra
for indications of a spectral cutoff, which singles out four sources of
particular interest. We find all sources to be compatible with a point-source
scenario. Multi-wavelength associations and, in particular, their infrared
color-color data indicate no source to be compatible with a dark matter origin,
and we find the majority of the candidates to probably originate from faint,
high-frequency peaked BL Lac type objects. We discuss possibilities to further
investigate source candidates and future prospects to search for dark matter
subhalos.
