Unveiling the nature of the unidentified gamma-ray sources I: a new method for the association of gamma-ray blazars

Abstract

We present a new method for identifying blazar candidates by examining the locus, i.e. the region occupied by the Fermi gamma-ray blazars in the three-dimensional color space defined by the WISE infrared colors. This method is a refinement of our previous approach that made use of the two-dimensional projection of the distribution of WISE gamma-ray emitting blazars (the Strip) in the three WISE color-color planes (Massaro et al. 2012a). In this paper, we define the three-dimensional locus by means of a Principal Component (PCs) analysis of the colors distribution of a large sample of blazars composed by all the ROMA-BZCAT sources with counterparts in the WISE All-Sky Catalog and associated to gamma-ray source in the second Fermi LAT catalog (the WISE Fermi Blazars sample, WFB). Our new procedure yields a total completeness of c~81% and total efficiency of e~97%. We also obtain local estimates of the efficiency and completeness as functions of the WISE colors and galactic coordinates of the candidate blazars. The catalog of all WISE candidate blazars associated to the WFB sample is also presented, complemented by archival multi-frequency information for the alternative associations. Finally, we apply the new association procedure to all gamma-ray blazars in the 2FGL and provide a catalog containing all the gamma-ray candidates blazars selected according to our procedure.

24 pages, 10 figures, accepted for publication in ApJS, 2 tables

References in corpus (7)

• Mid-Infrared Selection of AGN with the Wide-Field Infrared Survey Explorer. I. Characterizing WISE-Selected AGN in COSMOS
• Roma-BZCAT: A multifrequency catalogue of Blazars
• Characterizing the Mid-IR Extragalactic Sky with WISE and SDSS
• On the relation between AGN gamma-ray emission and parsec-scale radio jets
• Characterizing the Optical Variability of Bright Blazars: Variability-Based Selection of Fermi AGN
• Gamma-Ray Active Galactic Nucleus Type through Machine-Learning Algorithms
• 0FGL J1830.3+0617: A Fermi Blazar Near the Galactic Plane

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