Searching for an EBL attenuation signature in the Fermi/LAT 1st year
  catalog data
  Observations of distant sources of high-energy (HE) gamma-rays are affected
by attenuation resulting from the interaction of the gamma-rays with low energy
photons from the diffuse meta-galactic radiation fields at ultraviolet (UV) to
infrared (IR) wavelengths (Extragalactic Background Light; EBL). Recently, a
large data-set of HE observations from the 1st year survey of the Large Area
Telescope (LAT) instrument on-board of the Fermi satellite became available,
covering an energy range from 100 MeV up to 100 GeV. In this paper, the
potential of such large HE data-sets to probe the density of the EBL -
especially in the UV to optical - is explored. The data from the catalog is
investigated for an attenuation signature in the energy range 10-100 GeV and
the results are compared with the predictions from EBL model calculations. No
clear signature is found. The statistics are still limited by (1) the
sensitivity of Fermi/LAT to detect sources above 10 GeV, (2) the number of
firmly identified sources with known redshift, both which will improve over the
coming years.
