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|Title:||Refining the Associations of the Fermi Large Area Telescope Source Catalogs||Authors:||MASSARO, Francesco
Digel, S. W.
Smith, Howard A.
|Issue Date:||2015||Journal:||THE ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES||Number:||217||Issue:||1||First Page:||1||Abstract:||The Fermi-Large Area Telescope (LAT) First Source Catalog (1FGL) was released in 2010 February and the Fermi-LAT 2-Year Source Catalog (2FGL) appeared in 2012 April, based on data from 24 months of operation. Since they were released, many follow up observations of unidentified γ-ray sources have been performed and new procedures for associating γ-ray sources with potential counterparts at other wavelengths have been developed. Here we review and characterize all of the associations as published in the 1FGL and 2FGL catalogs on the basis of multifrequency archival observations. In particular, we located 177 spectra for the low-energy counterparts that were not listed in the previous Fermi catalogs, and in addition we present new spectroscopic observations of eight γ-ray blazar candidates. Based on our investigations, we introduce a new counterpart category of “candidate associations” and propose a refined classification for the candidate low-energy counterparts of the Fermi sources. We compare the 1FGL-assigned counterparts with those listed in 2FGL to determine which unassociated sources became associated in later releases of the Fermi catalogs. We also search for potential counterparts to all of the remaining unassociated Fermi sources. Finally, we prepare a refined and merged list of all of the associations of 1FGL plus 2FGL that includes 2219 unique Fermi objects. This is the most comprehensive and systematic study of all the associations collected for the γ-ray sources available to date. We conclude that 80% of the Fermi sources have at least one known plausible γ-ray emitter within their positional uncertainty regions.||Acknowledgments:||We thank the anonymous referee for useful comments that led to improvements in the paper. F.M. and G.T. also thank L. Costamante. This investigation is supported by the NASA grants NNX12AO97G and NNX13AP20G. The work by G.T. is supported by the ASI/INAF contract I/005/12/0. H.A.S. acknowledges partial support from NASA/JPL grants RSA 1369556 and 1369565. H.O.F. was funded by a postdoctoral UNAM grant and is currently granted by a Cátedra CONACyT para Jóvenes Investigadores. V.C. acknowledges funding by CONACyT research grant 151494 (México). We thank the staff at the Observatorio Astronómico Nacional in San Pedro Mártir (México) for all their help during the observation runs. 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 NASAs 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 National Aeronautics and Space Administration. 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, Duncan Campbell-Wilson, and the staff, Jeff Webb, Michael White, and John 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 Michael Large, whose expertise and vision made the project possible. 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 the National Aeronautics and Space Administration. This publication makes use of data products from 2MASS, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. Funding for SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web Site is http://www.sdss.org/. The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions.||URI:||http://hdl.handle.net/20.500.12386/23180||URL:||https://iopscience.iop.org/article/10.1088/0067-0049/217/1/2||ISSN:||0067-0049||DOI:||10.1088/0067-0049/217/1/2||Bibcode ADS:||2015ApJS..217....2M||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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