Discovery of Very-high-energy Emission from RGB J2243+203 and Derivation of Its Redshift Upper Limit

A. U. Abeysekara, S. Archambault, A. Archer, W. Benbow, R. Bird, R. Brose, M. Buchovecky, J. H. Buckley, V. Bugaev, M. Cerruti, M. P. Connolly, W. Cui, A. Falcone, Q. Feng, J. P. Finley, H. Fleischhack, L. Fortson, A. Furniss, G. H. Gillanders, S. GriffinJ. Grube, M. Hütten, D. Hanna, O. Hervet, J. Holder, T. B. Humensky, C. A. Johnson, P. Kaaret, P. Kar, N. Kelley-Hoskins, M. Kertzman, D. Kieda, M. Krause, F. Krennrich, S. Kumar, M. J. Lang, G. Maier, S. McArthur, P. Moriarty, R. Mukherjee, D. Nieto, S. O'Brien, R. A. Ong, A. N. Otte, N. Park, A. Petrashyk, M. Pohl, A. Popkow, E. Pueschel, J. Quinn

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3 Scopus citations


Very-high-energy (VHE; > 100 GeV) gamma-ray emission from the blazar RGB J2243+203 was discovered with the VERITAS Cherenkov telescope array, during the period between 2014 December 21 and 24. The VERITAS energy spectrum from this source can be fitted by a power law with a photon index of 4.6±0.5, and a flux normalization at 0.15 TeV of (6.3 ±1.1 10-10 cm-2 s-1 TeV-1 )10-2 1 1. The integrated Fermi-LAT flux from 1 to 100 GeV during the VERITAS detection is (4.1 ±0.8× 10 cm-2 s-1 ), which is an order of magnitude larger than the four-year-averaged flux in the same energy range reported in the 3FGL catalog, (4.0± 0.1× 10-9 cm-2s -1). The detection with VERITAS triggered observations in the X-ray band with the Swift-XRT. However, due to scheduling constraints Swift-XRT observations were performed 67 hr after the VERITAS detection, rather than simultaneously with the VERITAS observations. The observed X-ray energy spectrum between 2 and 10 keV can be fitted with a power law with a spectral index of 2.7±0.2, and the integrated photon flux in the same energy band is (3.6 ±0.6 10-13 cm-2 s-1 ). EBL-model-dependent upper limits of the blazar redshift have been derived. Depending on the EBL model used, the upper limit varies in the range from z < 0.9 to z < 1.1.

Original languageEnglish (US)
Article number7
JournalAstrophysical Journal, Supplement Series
Issue number1
StatePublished - Nov 2017

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  • Galaxies: individual (RGB J2243+203)


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