2014/04/11 by M. Nori, M. Giroletti, F. Massaro +4 · 2 citations
Earth and Planetary Sciences · Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Blazar #Dark Matter and Cosmic Phenomena #Earth Systems and Cosmic Evolution #Fermi Gamma-ray Space Telescope #Flux (metallurgy) #Radio spectrum #Sky #Spectral index #Spectral line #astro-ph.HE
paper · pdf · doi:10.1088/0067-0049/212/1/3
8 pages, 4 figures, 4 tables, ApJS published in 2014 (pre-proof version uploaded)
openalex publication_date 2014/04/11 · arxiv created 2015/03/10 · arxiv updated 2015/03/12 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
According to the Fermi Large Area Telescope Second Source Catalog (2FGL), about one-third of the γ-ray sources listed have no assigned counterparts at lower energies. Many statistical methods have been developed to find proper counterparts for these sources. We explore the sky area covered at low radio frequency by the Westerbork in the Southern Hemisphere (WISH) survey to search for blazar-like associations among the unidentified γ-ray sources (UGSs) listed in the 2FGL. Searching the WISH and NRAO Very Large Array Sky Survey radio surveys within the positional uncertainty regions of the 2FGL UGSs, we select as γ-ray blazar candidates the radio sources characterized by flat radio spectra between 352 MHz and 1400 MHz. We propose new γ-ray blazar associations for eight UGSs and we also discuss their spectral properties at low radio frequencies. We compare the radio flux density distribution of the low radio frequency γ-ray blazar candidates with that of γ-ray blazars associated with other methods. We find significant differences between these distributions. Finally, we discuss the results of this association method and its possible applicability to other regions of the sky and future radio surveys.