van Eldik C, Abramowski A, Acero F, Aharonian F, Akhperjanian AG, Anton G, Balzer A, Barnacka A, De Almeida UB, Bazer-Bachi AR, Becherini Y, Becker J, Behera B, Bernloehr K, Bochow A, Boisson C, Bolmont J, Bordas P, Borrel V, Brucker J, Brun F, Brun P, Bulik T, Buesching I, Carrigan S, Casanova S, Cerruti M, Chadwick PM, Charbonnier A, Chaves RCG, Cheesebrough A, Chounet LM, Clapson AC, Coignet G, Colom P, Conrad J, Dalton M, Daniel MK, Davids ID, Degrange B, Deil C, Dickinson HJ, Djannati-Atai A, Domainko W, Drury LO, Dubois F, Dubus G, Dyks J, Dyrda M, Egberts K, Eger P, Espigat P, Fallon L, Farnier C, Fegan S, Feinstein F, Fernandes MV, Fiasson A, Fontaine G, Foerster A, Fuessling M, Gallant YA, Gast H, Gerard L, Gerbig D, Giebels B, Glicenstein JF, Glueck B, Goret P, Göring D, Häffner S, Hague JD, Hampf D, Hauser M, Heinz S, Heinzelmann G, Henri G, Hermann G, Hinton JA, Hoffmann A, Hofmann W, Hofverberg P, Holler M, Horns D, Jacholkowska A, De Jager OC, Jahn C, Jamrozy M, Jung I, Kastendieck MA, Katarzynski K, Katz U, Kaufmann S, Keogh D, Khangulyan D, Khelifi B, Klochkov D, Kluzniak W, Kneiske TM, Komin N, Kosack K, Kossakowski R, Laffon H, Lamanna G, Lennarz D, Lohse T, Lopatin A, Lu CC, Marandon V, Marcowith A, Masbou J, Maurin D, Maxted NI, Mccomb TJL, Medina MC, Mehault J, Nguyen N, Moderski R, Moulin E, Naumann CL, Naumann-Godo M, De Naurois M, Nedbal D, Nekrassov D, Nicholas B, Niemiec J, Nolan SJ, Ohm S, Olive JF, Wilhelmi EDO, Opitz B, Ostrowski M, Panter M, Arribas MP, Pedaletti G, Pelletier G, Petrucci PO, Pita S, Puehlhofer G, Punch M, Quirrenbach A, Raue M, Rayner SM, Reimer A, Reimer O, Renaud M, De Los Reyes R, Rieger F, Ripken J, Rob L, Rosier-Lees S, Rowell G, Rudak B, Rulten CB, Ruppel J, Ryde F, Sahakian V, Santangelo A, Schlickeiser R, Schoeck FM, Schoenwald A, Schulz A, Schwanke U, Schwarzburg S, Schwemmer S, Shalchi A, Sikora M, Skilton JL, Sol H, Spengler G, Stawarz L, Steenkamp R, Stegmann C, Stinzing F, Stycz K, Sushch I, Szostek A, Tavernet JP, Terrier R, Tibolla O, Tluczykont M, Valerius K, Van Eldik C, Vasileiadis G, Venter C, Vialle JP, Viana A, Vincent P, Vivier M, Voelk HJ, Volpe F, Vorobiov S, Vorster M, Wagner SJ, Ward M, Wierzcholska A, Zajczyk A, Zdziarski AA, Zech A, Zechlin HS, Burnett TH, Hill AB (2011)
Publication Status: Published
Publication Type: Journal article, Original article
Publication year: 2011
Publisher: EDP Sciences
Book Volume: 529
Article Number: A49
DOI: 10.1051/0004-6361/201116545
Context. The H.E.S.S. Cherenkov telescope array has been surveying the Galactic plane for new VHE (>100 GeV) gamma-ray sources. Aims. We report on a newly detected point-like source, HESS J1943+213. This source coincides with an unidentified hard X-ray source IGR J19443+2117, which was proposed to have radio and infrared counterparts. Methods. We combine new H.E.S.S., Fermi/LAT and Nançay Radio Telescope observations with pre-existing non-simultaneous multi-wavelength observations of IGR J19443+2117 and discuss the likely source associations as well as the interpretation as an active galactic nucleus, a gamma-ray binary or a pulsar wind nebula. Results. HESS J1943+213 is detected at the significance level of 7.9σ (post-trials) at RA(J2000)= 19 4355 ± 1 ± 1 , Dec(J2000)= +21° 18'8" ± 17" ± 20". The source has a soft spectrum with photon index Γ = 3.1 ± 0.3 ± 0.2 and a flux above 470 GeV of (1.3 ± 0.2 ± 0.3) × 10 cm s . There is no Fermi/LAT counterpart down to a flux limit of 6 × 10 cm s in the 0.1-100 GeV energy range (95% confidence upper limit calculated for an assumed power-law model with a photon index Γ = 2.0). The data from radio to VHE gamma-rays do not show any significant variability. Conclusions. The lack of a massive stellar counterpart disfavors the binary hypothesis, while the soft VHE spectrum would be very unusual in case of a pulsar wind nebula. In addition, the distance estimates for Galactic counterparts places them outside of the Milky Way. All available observations favor an interpretation as an extreme, high-frequency peaked BL Lac object with a redshift z > 0.14. This would be the first time a blazar is detected serendipitously from ground-based VHE observations, and the first VHE AGN detected in the Galactic Plane. © 2011 ESO.
APA:
van Eldik, C., Abramowski, A., Acero, F., Aharonian, F., Akhperjanian, A.G., Anton, G.,... Hill, A.B. (2011). HESS J1943+213: A candidate extreme BL Lacertae object. Astronomy & Astrophysics, 529. https://doi.org/10.1051/0004-6361/201116545
MLA:
van Eldik, Christopher, et al. "HESS J1943+213: A candidate extreme BL Lacertae object." Astronomy & Astrophysics 529 (2011).
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