UNVEILING THE NATURE OF THE UNIDENTIFIED GAMMA-RAY SOURCES. III. GAMMA-RAY BLAZAR-LIKE COUNTERPARTS AT LOW RADIO FREQUENCIES

作者：Massaro F^*; D' Abrusco R; Giroletti M; Paggi A; Masetti N; Tosti G; Nori M; Funk S

来源：Astrophysical Journal, The - Supplement Series, 2013, 207(1): UNSP 4.

DOI：10.1088/0067-0049/207/1/4

• BL Lacertae objects: general
• galaxies: active
• gamma rays: galaxies
• gamma rays: general quasars: general
• radiation mechanisms: non-thermal
• radio continuum: galaxies

About one-third of the gamma-ray sources listed in the second Fermi Large Area Telescope catalog (2FGL) have no firmly established counterpart at lower energies and so are classified as unidentified gamma-ray sources (UGSs). Here, we propose a new approach to find candidate counterparts for the UGSs based on the 325 MHz radio survey performed with the Westerbork Synthesis Radio Telescope in the northern hemisphere. First, we investigate the low-frequency radio properties of blazars, the largest known population of gamma-ray sources; then we search for sources with similar radio properties combining the information derived from theWesterbork Northern Sky Survey (WENSS) with those of the NRAO Very Large Array Sky Survey. We present a list of candidate counterparts for 32 UGSs with at least one counterpart in the WENSS. We also performed an extensive research in the literature to look for infrared and optical counterparts of the gamma-ray blazar candidates selected using the low-frequency radio observations to confirm their nature. On the basis of our multifrequency research, we identify 23 new gamma-ray blazar candidates out of the 32 UGSs investigated. Comparison with previous results on the UGSs is also presented. Finally, we speculate on the advantages of using low-frequency radio observations to associate UGSs and to search for gamma-ray pulsar candidates.

• 出版日期2013-7