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|Title:||Optical Spectroscopic Observations of Gamma-ray Blazar Candidates. IV. Results of the 2014 Follow-up Campaign||Authors:||Ricci, F.
Smith, Howard A.
|Issue Date:||2015||Journal:||THE ASTRONOMICAL JOURNAL||Number:||149||Issue:||5||First Page:||1||Abstract:||The extragalactic γ-ray sky is dominated by the emission arising from blazars, one of the most peculiar classes of radio-loud active galaxies. Since the launch of Fermi several methods were developed to search for blazars as potential counterparts of unidentified γ-ray sources (UGSs). To confirm the nature of the selected candidates, optical spectroscopic observations are necessary. In 2013 we started a spectroscopic campaign to investigate γ-ray blazar candidates selected according to different procedures. The main goals of our campaign are: (1) to confirm the nature of these candidates, and (2) whenever possible, determine their redshifts. Optical spectroscopic observations will also permit us to verify the robustness of the proposed associations and check for the presence of possible source class contaminants to our counterpart selection. This paper reports the results of observations carried out in 2014 in the northern hemisphere with Kitt Peak National Observatory and in the southern hemisphere with the Southern Astrophysical Research telescopes. We also report three sources observed with the Magellan and Palomar telescopes. Our selection of blazar-like sources that could be potential counterparts of UGSs is based on their peculiar infrared colors and on their combination with radio observations both at high and low frequencies (i.e., above and below ̃1 GHz) in publicly available large radio surveys. We present the optical spectra of 27 objects. We confirm the blazar-like nature of nine sources that appear to be potential low-energy counterparts of UGSs. Then we present new spectroscopic observations of 10 active galaxies of uncertain type associated with Fermi sources, classifying all of them as blazars. In addition, we present the spectra for five known γ-ray blazars with uncertain redshift estimates and three BL Lac candidates that were observed during our campaign. We also report the case for WISE J173052.85-035247.2, candidate counterpart of the source 2FGL J1730.6-0353, which has no radio counterpart in the major radio surveys. We confirm that our selection of γ-ray blazars candidates can successfully indentify low-energy counterparts to Fermi unassociated sources and allow us to discover new blazars.||Acknowledgments:||We are grateful to D. Hammer and S. Points for their help scheduling, preparing, and performing the KPNO and the SOAR observations, respectively. We are grateful to F. La Franca for the fruitful discussions that significantly improved the paper. This investigation is supported by the NASA grants NNX12AO97G and NNX13AP20G. F. Ricci acknowledges the grants MIUR PRIN 2010–2011 and INAF-PRIN 2011. H. A. Smith acknowledges partial support from NASA/JPL grant RSAs 1369566, 1369556, and 1369565. The work by G. Tosti is supported by the ASI/INAF contract I/005/12/0. Part of this work is based on archival data, software or online services provided by the ASI Science Data Center. This research has made use of data obtained from the high-energy Astrophysics Science Archive Research Center (HEASARC) provided by NASA’s Goddard Space Flight Center; the SIMBAD database operated at CDS, Strasbourg, France; the NASA/IPAC Extragalactic Database (NED) operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the NASA. Part of this work is based on the NVSS (NRAO VLA Sky Survey): the National Radio Astronomy Observatory is operated by Associated Universities, Inc., under contract with the National Science Foundation and on the VLA low-frequency Sky Survey (VLSS). The Molonglo Observatory site manager, D. Campbell-Wilson, and the staff, J. Webb, M. White and J. Barry, are responsible for the smooth operation of Molonglo Observatory Synthesis Telescope (MOST) and the day-to-day observing programme of SUMSS. The SUMSS survey is dedicated to M. Large whose expertise and vision made the project possible. The MOST is operated by the School of Physics with the support of the Australian Research Council and the Science Foundation for Physics within the University of Sydney. 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 NASA. This publication makes use of data products from the 2MASS, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by NASA and NSF. This research has made use of the USNOFS Image and Catalogue Archive operated by the United States Naval Observatory, Flagstaff Station. 15 15 http://nofs.navy.mil/data/fchpix/ Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the NSF, the U.S. Department of Energy, NASA, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web Site is http://sdss.org/ . The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions. The WENSS project was a collaboration between the Netherlands Foundation for Research in Astronomy and the Leiden Observatory. We acknowledge the WENSS team consisted of G. de Bruyn, Y. Tang, R. Rengelink, G. Miley, H. Röttgering, M. Bremer, M. Bremer, W. Brouw, E. Raimond and D. Fullagar for the extensive work aimed at producing the WENSS catalog. TOPCAT 16 16 http://star.bris.ac.uk/∼mbt/topcat/ (Taylor 2005 ) for the preparation and manipulation of the tabular data and the images. The Aladin Java applet 17 17 http://aladin.u-strasbg.fr/aladin.gml was used to create the finding charts reported in this paper (Bonnarel et al. 2000 ). It can be started from the CDS (Strasbourg, France), from the CFA (Harvard, USA), from the ADAC (Tokyo, Japan), from the IUCAA (Pune, India), from the UKADC (Cambridge, UK), or from the CADC (Victoria, Canada).||URI:||http://hdl.handle.net/20.500.12386/23201||URL:||https://iopscience.iop.org/article/10.1088/0004-6256/149/5/160||ISSN:||0004-6256||DOI:||10.1088/0004-6256/149/5/160||Bibcode ADS:||2015AJ....149..160R||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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