Optical spectroscopic observations of gamma-ray blazar candidates. VII. Follow-up campaign in the southern hemisphere

• Published in: Astrophysics and space science 2017-12, Vol.362 (12), p.1-38, Article 228
• Main Authors: Peña-Herazo, H. A., Marchesini, E. J., Álvarez Crespo, N., Ricci, F., Massaro, F., Chavushyan, V., Landoni, M., Strader, J., Chomiuk, L., Cheung, C. C., Masetti, N., Jiménez-Bailón, E., D’Abrusco, R., Paggi, A., Milisavljevic, D., La Franca, F., Smith, H. A., Tosti, G.
• Format: Article
• Language: English
• Subjects: Astrobiology; Astronomy; Astrophysical research; Astrophysics; Astrophysics and Astroparticles; Cosmology; Gamma ray astronomy; Gamma rays; Observations and Techniques; Original Article; Physics; Physics and Astronomy; Quasars; Red shift; Southern Hemisphere; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Spectroscopy
• ISSN: 0004-640X; 1572-946X
• DOI: 10.1007/s10509-017-3208-7

Searching for low energy counterparts of γ -rays sources is one of the major challenges in modern γ -ray astronomy. In the third Fermi source catalog about 30% of detected sources are unidentified/unassociated Gamma-ray Sources (UGSs). We recently started an optical spectroscopic follow up campaign to confirm the blazar-like nature of candidates counterparts of UGSs. Here we report the spectra of 61 targets collected with the Southern Astrophysical Research Telescope (SOAR) between 2014 and the 2017. Our sample includes 33 potential counterparts of UGSs, selected on the basis of WISE colors, and 27 blazar candidates of uncertain type associated with gamma-ray sources of the last release of the Fermi catalog. We confirm the BZB nature of 20 sources lying within the positional uncertainty region of the UGSs. All the observed BCUs show blazar-like spectra, classified as 2 BZQs and 25 BZBs, for which we obtained 6 redshift estimates. Within the BCUs observations we report the redshift estimate for the BZB associated with, 3FGL J1106.4-3643 that is the second most distant BL Lac known to date, at z ≥ 1.084 .