The WISE Gamma-Ray Strip Parameterization: The Nature of the Gamma-Ray Active Galactic Nuclei of Uncertain Type
Articolo
Data di Pubblicazione:
2012
Abstract:
Despite the large number of discoveries made recently by Fermi, the origins of the so-called unidentified γ -ray
sources remain unknown. The large number of these sources suggests that there could be a population among
them that significantly contributes to the isotropic gamma-ray background and it is therefore crucial to understand
their nature. The first step toward a complete comprehension of the unidentified γ -ray source population is to
identify those that can be associated with blazars, the most numerous class of extragalactic sources in the γ -ray
sky. Recently, we discovered that blazars can be recognized and separated from other extragalactic sources using
the infrared (IR) WISE satellite colors. The blazar population delineates a remarkable and distinctive region of the
IR color–color space, the WISE blazar strip. In particular, the subregion delineated by the γ -ray emitting blazars
is even narrower and we named it the WISE Gamma-ray Strip (WGS). In this paper, we parameterize the WGS on
the basis of a single parameter s that we then use to determine if γ -ray active galactic nuclei of the uncertain type
(AGUs) detected by Fermi are consistent with the WGS and can be considered blazar candidates. We find that 54
AGUs out of a set of 60 analyzed have IR colors consistent with the WGS; only 6 AGUs are outliers. This result
implies that a very high percentage (i.e., in this sample about 90%) of the AGUs detected by Fermi are indeed
blazar candidates.
Tipologia CRIS:
03A-Articolo su Rivista
Keywords:
BL Lacertae objects: general , galaxies: active , gamma rays: general , radiation mechanisms:
non-thermal
Elenco autori:
F. Massaro;R. D'Abrusco;G. Tosti;M. Ajello;D. Gasparrini;J. E. Grindlay;Howard A. Smith
Link alla scheda completa:
Pubblicato in: