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Multiwavelenght observations of the previously unidentified blzar RX J0648.7+1516

  • We report on the VERITAS discovery of very high energy (VHE) gamma-ray emission above 200 GeV from the high-frequency-peaked BL Lac (HBL) object RX J0648.7+1516 (GB J0648+1516), associated with 1FGL J0648.8+1516. The photon spectrum above 200 GeV is fitted by a power law dN/dE = F-0(E/E-0)(-Gamma) with a photon index Gamma of 4.4 +/- 0.8(stat) +/- 0.3(syst) and a flux normalization F-0 of (2.3 +/- 0.5(stat) +/- 1.2(sys)) x 10(-11) TeV-1 cm(-2) s(-1) with E-0 = 300 GeV. No VHE variability is detected during VERITAS observations of RX J0648.7+1516 between 2010 March 4 and April 15. Following the VHE discovery, the optical identification and spectroscopic redshift were obtained using the Shane 3 m Telescope at the Lick Observatory, showing the unidentified object to be a BL Lac type with a redshift of z = 0.179. Broadband multiwavelength observations contemporaneous with the VERITAS exposure period can be used to subclassify the blazar as an HBL object, including data from the MDM observatory, Swift-UVOT, and X-Ray Telescope, andWe report on the VERITAS discovery of very high energy (VHE) gamma-ray emission above 200 GeV from the high-frequency-peaked BL Lac (HBL) object RX J0648.7+1516 (GB J0648+1516), associated with 1FGL J0648.8+1516. The photon spectrum above 200 GeV is fitted by a power law dN/dE = F-0(E/E-0)(-Gamma) with a photon index Gamma of 4.4 +/- 0.8(stat) +/- 0.3(syst) and a flux normalization F-0 of (2.3 +/- 0.5(stat) +/- 1.2(sys)) x 10(-11) TeV-1 cm(-2) s(-1) with E-0 = 300 GeV. No VHE variability is detected during VERITAS observations of RX J0648.7+1516 between 2010 March 4 and April 15. Following the VHE discovery, the optical identification and spectroscopic redshift were obtained using the Shane 3 m Telescope at the Lick Observatory, showing the unidentified object to be a BL Lac type with a redshift of z = 0.179. Broadband multiwavelength observations contemporaneous with the VERITAS exposure period can be used to subclassify the blazar as an HBL object, including data from the MDM observatory, Swift-UVOT, and X-Ray Telescope, and continuous monitoring at photon energies above 1 GeV from the Fermi Large Area Telescope (LAT). We find that in the absence of undetected, high-energy rapid variability, the one-zone synchrotron self-Compton (SSC) model overproduces the high-energy gamma-ray emission measured by the Fermi-LAT over 2.3 years. The spectral energy distribution can be parameterized satisfactorily with an external-Compton or lepto-hadronic model, which have two and six additional free parameters, respectively, compared to the one-zone SSC model.show moreshow less

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Author:E. Aliu, T. Aune, M. Beilicke, W. Benbow, M. Boettcher, A. Bouvier, S. M. Bradbury, J. H. Buckley, V. Bugaev, A. Cannon, A. Cesarini, L. Ciupik, M. P. Connolly, W. Cui, G. Decerprit, R. Dickherber, C. Duke, M. Errando, A. Falcone, Q. Feng, G. Finnegan, L. Fortson, A. Furniss, N. Galante, D. Gall, G. H. Gillanders, S. Godambe, S. Griffin, J. Grube, G. Gyuk, D. Hanna, B. Hivick, J. Holder, H. Huan, G. Hughes, C. M. Hui, T. B. Humensky, P. Kaaret, N. Karlsson, M. Kertzman, D. Kieda, H. Krawczynski, F. Krennrich, G. Maier, P. Majumdar, S. McArthur, A. McCann, P. Moriarty, R. Mukherjee, T. Nelson, R. A. Ong, M. Orr, A. N. Otte, N. Park, J. S. Perkins, A. Pichel, Martin PohlORCiDGND, H. Prokoph, J. Quinn, K. Ragan, L. C. Reyes, P. T. Reynolds, E. Roache, H. J. Rose, J. Ruppel, D. B. Saxon, G. H. Sembroski, C. Skole, A. W. Smith, D. Staszak, G. Tesic, M. Theiling, S. Thibadeau, K. Tsurusaki, J. Tyler, A. Varlotta, V. V. Vassiliev, S. P. Wakely, T. C. Weekes, A. Weinstein, D. A. Williams, B. Zitzer, S. Ciprini, M. Fumagalli, K. Kaplan, D. Paneque, J. X. Prochaska
DOI:https://doi.org/10.1088/0004-637X/742/2/127
ISSN:0004-637X (print)
Parent Title (English):The astrophysical journal : an international review of spectroscopy and astronomical physics
Publisher:IOP Publ. Ltd.
Place of publication:Bristol
Document Type:Article
Language:English
Year of first Publication:2011
Year of Completion:2011
Creating Corporation:VERITAS Collaboration
Release Date:2017/03/26
Tag:BL Lacertae objects: individual (RX J0648.7+1516, 1FGL J0648.8+1516, VER J0648+152); gamma rays: galaxies
Volume:742
Issue:2
Pagenumber:7
Funder:US Department of Energy; NSERC in Canada; Science Foundation Ireland (SFI ) [10/RFP/AST2748]; STFC in the UK; NASA [NNX10AF89G]; Fermi [NNX09AU18G]; NSF [AST-0548180]; US National Science Foundation; Smithsonian Institution
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie
Peer Review:Referiert