Abdalla H, Adam R, Aharonian F, Benkhali FA, Anguner EO, Arakawa M, Arcaro C, Armand C, Ashkar H, Backes M, Martins VB, Barnard M, Becherini Y, Berge D, Bernloehr K, Blackwell R, Bottcher M, Boisson C, Bolmont J, Bonnefoy S, Bregeon J, Breuhaus M, Brun F, Brun P, Bryan M, Büchele M, Bulik T, Bylund T, Capasso M, Caroff S, Carosi A, Casanova S, Cenuti M, Chand T, Chandra S, Chen A, Colafrancesco S, Curylo M, Davids ID, Deil C, Devin J, Dewilt P, Dirson L, Djannati-Atai A, Dmytriiev A, Donath A, Doroshenko , Drury LO, Dyks J, Egberts K, Emery G, Ernenwein JP, Eschbach S, Feijen K, Fegan S, Fiasson A, Fontaine G, Funk S, Fuessling M, Gabici S, Gallant YA, Gate F, Giavitto G, Glawion D, Glicenstein JF, Gottschall D, Grondin MH, Hahn J, Haupt M, Heinzelmann G, Henri G, Hermann G, Hinton JA, Hofmann W, Hoischen C, Holch TL, Holler M, Horns D, Huber D, Iwasaki H, Jamrozy M, Jankowsky D, Jankowsky F, Jardin-Blicq A, Jung-Richardt , Kastendieck MA, Katarzynski K, Katsuragawa M, Katz U, Khangulyan D, Khelifi B, King J, Klepser S, Kluzniak W, Komin N, Kosack K, Kostunin D, Kraus M, Lamanna G, Lau J, Lemiere A, Lemoine-Goumard M, Lenain JP, Leser E, Levy C, Lohse T, Lypova , Mackey J, Majumdar J, Malyshev D, Marandon , Marcowith A, Mares A, Mariaud C, Marti-Devesa G, Marx R, Maurin G, Meintjes PJ, Mitchell AMW, Moderski R, Mohamed M, Mohrmann L, Muller J, Moore C, Moulin E, Murach T, Nakashima S, De Naurois M, Ndiyavala H, Niederwanger F, Niemiec J, Oakes L, O'Brien P, Odaka H, Ohm S, Wilhelmi EDO, Ostrowski M, Oya , Panter M, Parsons RD, Perennes C, Petrucci PO, Peyaud B, Piel Q, Pita S, Poireau , Noel AP, Prokhorov DA, Puehlhofer G, Punch M, Quirrenbach A, Raab S, Rauth R, Reimer A, Reimer O, Remy Q, Renaud M, Rieger F, Rinchiuso L, Romoli C, Rowell G, Rudak B, Ruiz-Velasco E, Sahakian , Saito S, Sanchez DA, Santangelo A, Sasaki M, Schlickeiser R, Schuessler F, Schulz A, Schutte H, Schwanke U, Schwemmer S, Seglar-Arroyo M, Senniappan M, Seyffert AS, Shafi N, Shiningayamwe K, Simoni R, Sinha A, Sol H, Specovius A, Spir-Jacob M, Stawarz L, Steenkamp R, Stegmann C, Steppa C, Takahashi T, Tavernier T, Taylor AM, Terrier R, Tiziani D, Tluczykont M, Trichard C, Tsirou M, Tsuji N, Tuffs R, Uchiyama Y, Van Der Walt DJ, van Eldik C, Van Rensburg C, Van Soelen B, Vasileiadis G, Veh J, Venter C, Vincent P, Vink J, Voisin F, Voelk HJ, Vuillaume T, Wadiasingh Z, Wagner SJ, White R, Wierzcholska A, Yang R, Yoneda H, Zacharias M, Zanin R, Zdziarski AA, Zech A, Ziegler A, Zorn J, Zywucka NN, Smith PS (2020)
Publication Type: Journal article, Original article
Publication year: 2020
Book Volume: 633
Article Number: A162
DOI: 10.1051/0004-6361/201935906
Context. Flat-spectrum radio-quasars (FSRQs) are rarely detected at very high energies (E& x2004;>=& x2004;100 GeV) due to their low-frequency-peaked spectral energy distributions. At present, only six FSRQs are known to emit very high-energy (VHE) photons, representing only 7% of the VHE extragalactic catalog, which is largely dominated by high-frequency-peaked BL Lacertae objects. Aims. Following the detection of MeV-GeV gamma-ray flaring activity from the FSRQ PKS 0736+017 (z& x2004;=& x2004;0.189) with Fermi-LAT, the H.E.S.S. array of Cherenkov telescopes triggered target-of-opportunity (ToO) observations on February 18, 2015, with the goal of studying the gamma-ray emission in the VHE band. Methods. H.E.S.S. ToO observations were carried out during the nights of February 18, 19, 21, and 24, 2015. Together with Fermi-LAT, the multi-wavelength coverage of the flare includes Swift observations in soft X-ray and optical-UV bands, and optical monitoring (photometry and spectro-polarimetry) by the Steward Observatory, and the ATOM, the KAIT, and the ASAS-SN telescopes. Results. VHE emission from PKS 0736+017 was detected with H.E.S.S. only during the night of February 19, 2015. Fermi-LAT data indicate the presence of a gamma-ray flare, peaking at the time of the H.E.S.S. detection, with a flux doubling timescale of around six hours. The gamma-ray flare was accompanied by at least a 1 mag brightening of the non-thermal optical continuum. No simultaneous observations at longer wavelengths are available for the night of the H.E.S.S. detection. The gamma-ray observations with H.E.S.S. and Fermi-LAT are used to put constraints on the location of the gamma-ray emitting region during the flare: it is constrained to be just outside the radius of the broad-line region r(BLR) with a bulk Lorentz factor Gamma& x2004;similar or equal to& x2004;20, or at the level of the radius of the dusty torus r(torus) with Gamma& x2004;similar or equal to& x2004;60. Conclusions. PKS 0736+017 is the seventh FSRQ known to emit VHE photons, and at z& x2004;=& x2004;0.189 is the nearest so far. The location of the gamma-ray emitting region during the flare can be tightly constrained thanks to opacity, variability, and collimation arguments.
APA:
Abdalla, H., Adam, R., Aharonian, F., Benkhali, F.A., Anguner, E.O., Arakawa, M.,... Smith, P.S. (2020). HESS detection of very high-energy gamma-ray emission from the quasar PKS 0736+017. Astronomy & Astrophysics, 633. https://dx.doi.org/10.1051/0004-6361/201935906
MLA:
Abdalla, H., et al. "HESS detection of very high-energy gamma-ray emission from the quasar PKS 0736+017." Astronomy & Astrophysics 633 (2020).
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