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A search for very high-energy flares from the microquasars GRS 1915+105, Circinus X-1, and V4641 Sgr using contemporaneous H.E.S.S. and RXTE observations.

Abdalla, H. and Abramowski, A. and Aharonian, F. and Benkhali, F. Ait and Akhperjanian, A. G. and Angüner, E. O. and Arrieta, M. and Aubert, P. and Backes, M. and Balzer, A. and Barnard, M. and Becherini, Y. and Tjus, J. Becker and Berge, D. and Bernhard, S. and Bernlöhr, K. and Birsin, E. and Blackwell, R. and Böttcher, M. and Boisson, C. and Bolmont, J. and Bordas, P. and Bregeon, J. and Brun, F. and Brun, P. and Bryan, M. and Bulik, T. and Capasso, M. and Carr, J. and Casanova, S. and Chadwick, P. M. and Chakraborty, N. and Chalme-Calvet, R. and Chaves, R. C.G. and Chen, A. and Chevalier, J. and Chrétien, M. and Colafrancesco, S. and Cologna, G. and Condon, B. and Conrad, J. and Couturier, C. and Cui, Y. and Davids, I. D. and Degrange, B. and Deil, C. and deWilt, P. and Dickinson, H. J. and Djannati-Ataï, A. and Domainko, W. and Donath, A. and Drury, L.O’C. and Dubus, G. and Dutson, K. and Dyks, J. and Dyrda, M. and Edwards, T. and Egberts, K. and Eger, P. and Ernenwein, J.-P. and Eschbach, S. and Farnier, C. and Fegan, S. and Fernandes, M. V. and Fiasson, A. and Fontaine, G. and Förster, A. and Funk, S. and Füßling, M. and Gabici, S. and Gajdus, M. and Gallant, Y. A. and Garrigoux, T. and Giavitto, G. and Giebels, B. and Glicenstein, J. F. and Gottschall, D. and Goyal, A. and Grondin, M.-H. and Grudzińska, M. and Hadasch, D. and Hahn, J. and Hawkes, J. and Heinzelmann, G. and Henri, G. and Hermann, G. and Hervet, O. and Hillert, A. and Hinton, J. A. and Hofmann, W. and Hoischen, C. and Holler, M. and Horns, D. and Ivascenko, A. and Jacholkowska, A. and Jamrozy, M. and Janiak, M. and Jankowsky, D. and Jankowsky, F. and Jingo, M. and Jogler, T. and Jouvin, L. and Jung-Richardt, I. and Kastendieck, M. A. and Katarzyński, K. and Katz, U. and Kerszberg, D. and Khélifi, B. and Kieffer, M. and King, J. and Klepser, S. and Klochkov, D. and Kluźniak, W. and Kolitzus, D. and Komin, Nu. and Kosack, K. and Krakau, S. and Kraus, M. and Krayzel, F. and Krüger, P. P. and Laffon, H. and Lamanna, G. and Lau, J. and Lees, J.-P. and Lefaucheur, J. and Lefranc, V. and Lemière, A. and Lemoine-Goumard, M. and Lenain, J.-P. and Leser, E. and Lohse, T. and Lorentz, M. and Liu, R. and Lypova, I. and Marandon, V. and Marcowith, A. and Mariaud, C. and Marx, R. and Maurin, G. and Maxted, N. and Mayer, M. and Meintjes, P. J. and Menzler, U. and Meyer, M. and Mitchell, A. M.W. and Moderski, R. and Mohamed, M. and Morå, K. and Moulin, E. and Murach, T. and Naurois, M. de and Niederwanger, F. and Niemiec, J. and Oakes, L. and Odaka, H. and Öttl, S. and Ohm, S. and Ostrowski, M. and Oya, I. and Padovani, M. and Panter, M. and Parsons, R. D. and Arribas, M. Paz and Pekeur, N. W. and Pelletier, G. and Petrucci, P.-O. and Peyaud, B. and Pita, S. and Poon, H. and Prokhorov, D. and Prokoph, H. and Pühlhofer, G. and Punch, M. and Quirrenbach, A. and Raab, S. and Reimer, A. and Reimer, O. and Renaud, M. and los Reyes, R. de and Rieger, F. and Romoli, C. and Rosier-Lees, S. and Rowell, G. and Rudak, B. and Rulten, C. B. and Sahakian, V. and Salek, D. and Sanchez, D. A. and Santangelo, A. and Sasaki, M. and Schlickeiser, R. and Schüssler, F. and Schulz, A. and Schwanke, U. and Schwemmer, S. and Seyffert, A. S. and Shafi, N. and Shilon, I. and Simoni, R. and Sol, H. and Spanier, F. and Spengler, G. and Spies, F. and Stawarz, Ł. and Steenkamp, R. and Stegmann, C. and Stinzing, F. and Stycz, K. and Sushch, I. and Tavernet, J.-P. and Tavernier, T. and Taylor, A. M. and Terrier, R. and Tluczykont, M. and Trichard, C. and Tuffs, R. and van der Walt, J. and Eldik, C. van and Soelen, B. van and Vasileiadis, G. and Veh, J. and Venter, C. and Viana, A. and Vincent, P. and Vink, J. and Voisin, F. and Völk, H. J. and Vuillaume, T. and Wadiasingh, Z. and Wagner, S. J. and Wagner, P. and Wagner, R. M. and White, R. and Wierzcholska, A. and Willmann, P. and Wörnlein, A. and Wouters, D. and Yang, R. and Zabalza, V. and Zaborov, D. and Zacharias, M. and Zdziarski, A. A. and Zech, A. and Zefi, F. and Ziegler, A. and Żywucka, N. (2017) 'A search for very high-energy flares from the microquasars GRS 1915+105, Circinus X-1, and V4641 Sgr using contemporaneous H.E.S.S. and RXTE observations.', Astronomy & astrophysics., 612 . A10.


Context. Microquasars are potential γ-ray emitters. Indications of transient episodes of γ-ray emission were recently reported in at least two systems: Cyg X-1 and Cyg X-3. The identification of additional γ-ray-emitting microquasars is required to better understand how γ-ray emission can be produced in these systems. Aim. Theoretical models have predicted very high-energy (VHE) γ-ray emission from microquasars during periods of transient outburst. Observations reported herein were undertaken with the objective of observing a broadband flaring event in the γ-ray and X-ray bands. Methods. Contemporaneous observations of three microquasars, GRS 1915+105, Circinus X-1, and V4641 Sgr, were obtained using the High Energy Spectroscopic System (H.E.S.S.) telescope array and the Rossi X-ray Timing Explorer (RXTE) satellite. X-ray analyses for each microquasar were performed and VHE γ-ray upper limits from contemporaneous H.E.S.S. observations were derived. Results. No significant γ-ray signal has been detected in any of the three systems. The integral γ-ray photon flux at the observational epochs is constrained to be I(>560 GeV) < 7.3 × 10−13 cm−2 s−1, I(>560 GeV ) < 1.2 × 10−12 cm−2 s−1, and I(>240 GeV) < 4.5 × 10−12 cm−2 s−1 for GRS 1915+105, Circinus X-1, and V4641 Sgr, respectively. Conclusions. The γ-ray upper limits obtained using H.E.S.S. are examined in the context of previous Cherenkov telescope observations of microquasars. The effect of intrinsic absorption is modelled for each target and found to have negligible impact on the flux of escaping γ-rays. When combined with the X-ray behaviour observed using RXTE, the derived results indicate that if detectable VHE γ-ray emission from microquasars is commonplace, then it is likely to be highly transient.

Item Type:Article
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Publisher statement:Reproduced with permission from Astronomy & Astrophysics, © ESO 2018
Date accepted:28 February 2017
Date deposited:26 April 2018
Date of first online publication:09 April 2017
Date first made open access:26 April 2018

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