Optical spectroscopic observations of gamma-ray blazar candidates. X. Results from the 2018–2019 SOAR and OAN-SPM observations of blazar candidates of uncertain type
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The fourth Fermi Large Area Telescope Source Catalog (4FGL) lists over 5000 \(\gamma\)-ray sources with statistical significance above \(4\sigma\). About 23% of the sources listed in this catalog are unidentified/unassociated \(\gamma\)-ray sources while ∼26% of the sources are classified as blazar candidates of uncertain type (BCUs), lacking optical spectroscopic information. To probe the blazar nature of candidate counterparts of UGSs and BCUs, we started our optical spectroscopic follow up campaign in 2012, which up to date account for more than 350 observed sources. In this paper, the tenth of our campaign, we report on the spectroscopic observations of 37 sources, mostly BCUs, whose observations were carried out predominantly at the Observatorio Astronómico Nacional San Pedro Mártir and the Southern Astrophysical Research Observatory between August 2018 and September 2019. We confirm the BL Lac nature of 27 sources and the flat spectrum radio quasar nature of three sources. The remaining ones are classified as six BL Lacs galaxy-dominated and one normal galaxy. We were also able to measure the redshifts for 20 sources, including 10 BL Lacs. As in previous analyses, the largest fraction of BCUs revealed to be BL Lac objects.
KeywordsGalaxies: active Galaxies: BL Lacertae objects Quasars: general Surveys Radiation mechanisms: non-thermal
This work was supported by FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) under grants 2016/25484-9 and 2018/24801-6 (R.M.). R.A.A-A. and H.P. acknowledge support from the CONACyT program for Ph.D. studies. The work of F.M. and A.P. is partially supported by the “Departments of Excellence 2018–2022” Grant awarded by the Italian Ministry of Education, University and Research (MIUR) (L. 232/2016) and made use of resources provided by the Compagnia di San Paolo for the grant awarded on the BLENV project (S1618_L1_MASF_01) and by the Ministry of Education, Universities and Research for the grant MASF_FFABR_17_01. F.M. also acknowledges financial contribution from the agreement ASI-INAF n.2017-14-H.0 while A.P. the financial support from the Consorzio Interuniversitario per la Fisica Spaziale (CIFS) under the agreement related to the grant MASF_ CONTR_FIN_18_02. F.R. acknowledges support from FONDECYT Postdoctorado 3180506 and CONICYT project Basal AFB-170002. C.C.C. at NRL was supported by the Chief of Naval Research.
This research made use of Astropy,3 a community-developed core Python package for Astronomy (Astropy Collaboration 2013, 2018), ccdproc, an Astropy package for image reduction (Craig et al. 2015), and TOPCAT4 (Taylor 2005) for the preparation and manipulation of the tabular data.
This project makes use of data products from the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, Inovações e Comunicações (MCTIC) da República Federativa do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).
This project makes use of spectroscopic observations acquired at the 2.1 m telescope of the Observatorio Astronómico Nacional San Pedro Mártir (OAN-SPM), Baja California, México. We also thank the staff at the Observatorio Astrofísico Guillermo Haro (OAGH) for all their help during the observation runs.
This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration.
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