Discovery of the hard spectrum VHE gamma-ray source HESS J1641-463
Creators: name: Collaboration, H. E. S. S.
name: :
name: Abramowski, A.
name: Aharonian, F.
name: Benkhali, F. Ait
name: Akhperjanian, A. G.
name: Angüner, E. O.
name: Backes, M.
name: Balenderan, S.
name: Balzer, A.
name: Barnacka, A.
name: Becherini, Y.
name: Tjus, J. Becker
name: Berge, D.
name: Bernhard, S.
name: Bernlöhr, K.
name: Birsin, E.
name: Biteau, J.
name: Böttcher, M.
name: Boisson, C.
name: Bolmont, J.
name: Bordas, P.
name: Bregeon, J.
name: Brun, F.
name: Brun, P.
name: Bryan, M.
name: Bulik, T.
name: Carrigan, S.
name: Casanova, S.
name: Chadwick, P. M.
name: Chakraborty, N.
name: Chalme-Calvet, R.
name: Chaves, R. C. G.
name: Chrétien, M.
name: Colafrancesco, S.
name: Cologna, G.
name: Conrad, J.
name: Couturier, C.
name: Cui, Y.
name: Dalton, M.
name: Davids, I. D.
name: Degrange, B.
name: Deil, C.
name: deWilt, P.
name: Djannati-Ataï, A.
name: Domainko, W.
name: Donath, A.
name: Drury, L. O'C.
name: Dubus, G.
name: Dutson, K.
name: Dyks, J.
name: Dyrda, M.
name: Edwards, T.
name: Egberts, K.
name: Eger, P.
name: Espigat, P.
name: Farnier, C.
name: Fegan, S.
name: Feinstein, F.
name: Fernandes, M. V.
name: Fernandez, D.
name: Fiasson, A.
name: Fontaine, G.
name: Förster, A.
name: Füßling, M.
name: Gabici, S.
name: Gajdus, M.
name: Gallant, Y. A.
name: Garrigoux, T.
name: Giavitto, G.
name: Giebels, B.
name: Glicenstein, J. F.
name: Gottschall, D.
name: Grondin, M. -H.
name: Grudzińska, M.
name: Hadasch, D.
name: Häffner, S.
name: Hahn, J.
name: Harris, J.
name: Heinzelmann, G.
name: Henri, G.
name: Hermann, G.
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name: Hillert, A.
name: Hinton, J. A.
name: Hofmann, W.
name: Hofverberg, P.
name: Holler, M.
name: Horns, D.
name: Ivascenko, A.
name: Jacholkowska, A.
name: Jahn, C.
name: Jamrozy, M.
name: Janiak, M.
name: Jankowsky, F.
name: Jung-Richardt, I.
name: Kastendieck, M. A.
name: Katarzyński, K.
name: Katz, U.
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name: Klepser, S.
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name: Renaud, M.
name: Reyes, R. de los
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name: Rowell, G.
name: Rudak, B.
name: Rulten, C. B.
name: Sahakian, V.
name: Salek, D.
name: Sanchez, D. A.
name: Santangelo, A.
name: Schlickeiser, R.
name: Schüssler, F.
name: Schulz, A.
name: Schwanke, U.
name: Schwarzburg, S.
name: Schwemmer, S.
name: Sol, H.
name: Spanier, F.
name: Spengler, G.
name: Spies, F.
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name: Steenkamp, R.
name: Stegmann, C.
name: Stinzing, F.
name: Stycz, K.
name: Sushch, I.
name: Tavernet, J. -P.
name: Tavernier, T.
name: Taylor, A. M.
name: Terrier, R.
name: Tluczykont, M.
name: Trichard, C.
name: Valerius, K.
name: van Eldik, C.
name: van Soelen, B.
name: Vasileiadis, G.
name: Veh, J.
name: Venter, C.
name: Viana, A.
name: Vincent, P.
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name: Völk, H. J.
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name: Wagner, S. J.
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name: Weidinger, M.
name: Weitzel, Q.
name: White, R.
name: Wierzcholska, A.
name: Willmann, P.
name: Wörnlein, A.
name: Wouters, D.
name: Yang, R.
name: Zabalza, V.
name: Zaborov, D.
name: Zacharias, M.
name: Zdziarski, A. A.
name: Zech, A.
name: Zechlin, H. -S.
name: Fukui, Y.
name: Sano, H.
name: Fukuda, T.
name: Yoshiike, S.
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: This letter reports the discovery of a remarkably hard spectrum source, HESS J1641-463, by the High Energy Stereoscopic System (H.E.S.S.) in the very-high energy (VHE) domain. HESS J1641-463 remained unnoticed by the usual analysis techniques due to confusion with the bright nearby source HESS J1640-465. It emerged at a significance level of 8.5 standard deviations after restricting the analysis to events with energies above 4 TeV. It shows a moderate flux level of F(E &gt; 1 TeV) = (3.64 +/- 0.44_stat +/- 0.73_sys) x 10^-13 cm^-2s-1, corresponding to 1.8% of the Crab Nebula flux above the same energy, and a hard spectrum with a photon index of Gamma = 2.07 +/- 0.11_stat +/- 0.20_sys. It is a point-like source, although an extension up to Gaussian width of sigma = 3 arcmin cannot be discounted due to uncertainties in the H.E.S.S. PSF. The VHE gamma-ray flux of HESS J1641-463 is found to be constant over the observed period when checking time binnings from year-by-year to the 28 min exposures timescales. HESS J1641-463 is positionally coincident with the radio supernova remnant SNR G338.5+0.1. No X-ray candidate stands out as a clear association, however Chandra and XMM-Newton data reveal some potential weak counterparts. Various VHE gamma-ray production scenarios are discussed. If the emission from HESS J1641-463 is produced by cosmic ray protons colliding with the ambient gas, then their spectrum must extend close to 1 PeV. This object may represent a source population contributing significantly to the galactic cosmic ray flux around the knee.
description: 24 pages, 4 figures. Published version