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Gamma-Ray Emission from Two Blazars Behind the Galactic Plane: B2013+370 and B2023+336

Kara, E. and Errando, M. and Max-Moerbeck, W. and Aliu, E. and Böttcher, M. and Fortin, P. and Halpern, J. P. and Mukherjee, R. and Readhead, A. C. S. and Richards, J. L. (2012) Gamma-Ray Emission from Two Blazars Behind the Galactic Plane: B2013+370 and B2023+336. Astrophysical Journal, 746 (2). Art. No. 159. ISSN 0004-637X. doi:10.1088/0004-637X/746/2/159. https://resolver.caltech.edu/CaltechAUTHORS:20120321-095403778

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Abstract

B2013+370 and B2023+336 are two blazars at low-galactic latitude that were previously proposed to be the counterparts for the EGRET unidentified sources 3EG J2016+3657 and 3EG J2027+3429. Gamma-ray emission associated with the EGRET sources has been detected by the Fermi Gamma-ray Space Telescope, and the two sources, 1FGL J2015.7+3708 and 1FGL J2027.6+3335, have been classified as unidentified in the 1 year catalog. This analysis of the Fermi Large Area Telescope (LAT) data collected during 31 months reveals that the 1FGL sources are spatially compatible with the blazars and are significantly variable, supporting the hypothesis of extragalactic origin for the gamma-ray emission. The gamma-ray light curves are compared with 15 GHz radio light curves from the 40 m telescope at the Owens Valley Radio Observatory. Simultaneous variability is seen in both bands for the two blazar candidates. The study is completed with the X-ray analysis of 1FGL J2015.7+3708 using Swift observations that were triggered in 2010 August by a Fermi-detected flare. The resulting spectral energy distribution shows a two-component structure typical of blazars. We also identify a second source in the field of view of 1FGL J2027.6+3335 with similar characteristics to the known LAT pulsars. This study gives solid evidence favoring blazar counterparts for these two unidentified EGRET and Fermi sources, supporting the hypothesis that a number of unidentified gamma-ray sources at low-galactic latitudes are indeed of extragalactic origin.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/0004-637X/746/2/159DOIUNSPECIFIED
http://iopscience.iop.org/0004-637X/746/2/159/PublisherUNSPECIFIED
ORCID:
AuthorORCID
Kara, E.0000-0003-0172-0854
Max-Moerbeck, W.0000-0002-5491-5244
Readhead, A. C. S.0000-0001-9152-961X
Additional Information:© 2012 American Astronomical Society. Received 2011 November 8; accepted 2011 December 12; published 2012 February 2. This research is supported by the NASA grants NNX09AU14G and NNX10AP66G, and the US National Science Foundation grant Phys-0855627. W.M. acknowledges support from the US Department of State and the Comisiόn Nacional de Investigaciόn Científica y Tecnolόgica (CONICYT) in Chile for a Fulbright- CONICYT scholarship. The authors thank Diego Tescaro for providing an alternative code to evaluate the discrete correlation function and Vito Sguera for sharing the X-ray spectra of B2023+336. W.M. and J.R. thank Joseph Lazio for a helpful discussion about extreme scattering events. The OVRO 40 m monitoring program is supported in part by NASA grants NNX08AW31G and NNG06GG1G and NSF grant AST-0808050. The Fermi LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States; the Commissariat à l’Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucléaire et de Physique des Particules in France; the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy; the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK), and Japan Aerospace Exploration Agency (JAXA) in Japan; and the K. A. Wallenberg Foundation, the Swedish Research Council, and the Swedish National Space Board in Sweden. Additional support for science analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d’ Études Spatiales in France.
Funders:
Funding AgencyGrant Number
NASANNX09AU14G
NASANNX10AP66G
NSFPhys-0855627
Department of StateUNSPECIFIED
NASANNX08AW31G
NASANNG06GG1G
NSFAST-0808050
NASAUNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Commissariat à l'Energie Atomique (CEA) (France)UNSPECIFIED
Agenzia Spaziale Italiana (ASI)UNSPECIFIED
Ministry of Education, Culture, Sports, Science and Technology (MEXT)UNSPECIFIED
High Energy Accelerator Research Organization (KEK)UNSPECIFIED
Japan Aerospace Exploration Agency (JAXA)UNSPECIFIED
K. A. Wallenberg FoundationUNSPECIFIED
Swedish Research CouncilUNSPECIFIED
Swedish National Space BoardUNSPECIFIED
Istituto Nazionale di Fisica Nucleare (Italy)UNSPECIFIED
Centre National d'Études Spatiales (CNES) (France)UNSPECIFIED
Comisiόn Nacional de Investigaciόn Científica y Technolόgica (CONICYT)UNSPECIFIED
Centre National de la Recherche Scientifique/Institut National de Physique Nucléaire et de Physique des Particules (France)UNSPECIFIED
Subject Keywords: galaxies: individual (B2013+370, B2023+336); gamma rays: galaxies
Issue or Number:2
DOI:10.1088/0004-637X/746/2/159
Record Number:CaltechAUTHORS:20120321-095403778
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20120321-095403778
Official Citation: Gamma-Ray Emission from Two Blazars Behind the Galactic Plane: B2013+370 and B2023+336 E. Kara et al. 2012 ApJ 746 159
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:29795
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:23 Mar 2012 14:46
Last Modified:09 Nov 2021 19:30

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