Massaro, F.D'Abrusco, R.Tosti, G.Ajello, M.Gasparrini, D.Grindlay, J. E.Smith, Howard A.2019-09-252012Massaro, F., R. D’Abrusco, G. Tosti, M. Ajello, D. Gasparrini, J. E. Grindlay, and Howard A. Smith. 2012. “THE WISE GAMMA-RAY STRIP PARAMETERIZATION: THE NATURE OF THE GAMMA-RAY ACTIVE GALACTIC NUCLEI OF UNCERTAIN TYPE.” The Astrophysical Journal 750 (2): 138. https://doi.org/10.1088/0004-637x/750/2/138.0004-637X1538-4357http://nrs.harvard.edu/urn-3:HUL.InstRepos:41399799Despite the large number of discoveries made recently by Fermi, the origins of the so-called unidentified gamma-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 gamma-ray source population is to identify those that can be associated with blazars, the most numerous class of extragalactic sources in the gamma-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 gamma-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 gamma-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.en-USJournal Article2019-09-2510.1088/0004-637X/750/2/138