Wednesday, March 21, 2012
IPAC Astronomy Lunch Seminar
A "WISE" view of the gamma-ray sky
Francesco Massaro, Stanford
One of the main scientific objectives of the recent Fermi mission is unveiling the nature of the unidentified gamma-ray sources (UGSs). Despite the large improvements of Fermi in the gamma-ray source localization with respect to the past gamma-ray missions, about 1/3 of the Fermi detected objects still do not have yet a low energy counterpart associated. Recently, we discovered that blazars, the rarest and the most gamma-ray detected class of Active Galactic Nuclei, can be recognized and separated from other extragalactic sources using the IR colors. This discovery has been found thanks to the all-sky survey of the recent NASA mission: Wide-field Infrared Survey Explorer (WISE). Consequently, we built an association method for the gamma-ray sources able to recognize if there is a blazar candidate within the positional error region of a generic gamma-ray source. With this new IR diagnostic tool, we searched for blazar candidates within the UGS sample of the second Fermi gamma-ray catalog (2FGL). For the first time, we have been able to provide a candidate counterpart for 187 out of 313 UGSs analyzed, having the same infrared properties of the gamma-ray emitting blazars. I will discuss on the IR gamma-ray connection for the blazar population and I will illustrate our association method together with the main results. Finally, I also show how this new association procedure could be applied to the soft gamma-ray sources that are still unidentified in the 4th INTEGRAL catalog.