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Simultaneous HESS and Chandra observations of Sagitarius A(star) during an X-ray flare

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posted on 24.10.2012, 08:53 by F. Aharonian, A. G. Akhperjanian, de Almeida UB, A. R. Bazer-Bachi, Y. Becherini, B. Behera, W. Benbow, K. Bernloehr, C. Boisson, A. Bochow, V. Borrel, G. Fontaine, J. -. P. Tavernet, R. Terrier, O. Tibolla, van Eldik C, G. Vasileiadis, C. Venter, J. P. Vialle, P. Vincent, L. -. M. Chounet, K. J. Orford, M. Vivier, H. J. Voelk, M. Fuessling, R. Buehler, F. Volpe, S. J. Wagner, M. Ward, A. A. Zdziarski, A. Zech, T. Bulik, D. Hauser, A. C. Clapson, I. Buesching, T. Boutelier, S. Carrigan, S. Gabici, P. M. Chadwick, G. Coignet, M. Dalton, B. Degrange, C. Deil, M. Hauser, Y. A. Gallant, D. Keogh, H. J. Dickinson, A. Djannati-Atai, W. Domainko, L. O. Drury, F. Dubois, G. Dubus, J. Dyks, M. Dyrda, S. Heinz, K. Egberts, D. Emmanoulopoulos, N. Komin, L. Gerard, P. Espigat, C. Farnier, F. Feinstein, A. Fiasson, A. Foerster, B. Giebels, G. Heinzelmann, J. F. Glicenstein, B. Glueck, P. Goret, K. Kosack, C. Hadjichristidis, G. Henri, G. Hermann, J. A. Hinton, A. Hoffmann, G. Lamanna, I. Braun, W. Hofmann, M. Holleran, J. L. Osborne, S. Hoppe, D. Horns, A. Jacholkowska, de Jager OC, I. Jung, K. Katarzynski, S. Kaufmann, A. Quirrenbach, J. -. P. Lenain, E. Kendziorra, M. Kerschhaggl, D. Khangulyan, M. Ostrowski, B. Khelifi, T. Lohse, V. Marandon, J. M. Martin, O. Martineau-Huynh, B. C. Raubenheimer, M. Panter, A. Shalchi, A. Marcowith, D. Maurin, T. J. L. McComb, M. C. Medina, R. Moderski, E. Moulin, M. Naumann-Godo, de Naurois M, M. Raue, D. Nedbal, D. Nekrassov, J. L. Skilton, G. Pedaletti, J. Niemiec, S. J. Nolan, S. Ohm, J. -. F. Olive, E. D. O. Wilhelmi, G. Pelletier, S. M. Rayner, P. -. O. Petrucci, S. Pita, G. Puehlhofer, H. Sol, M. Punch, M. Renaud, F. Rieger, J. Ripken, L. Rob, D. Spangler, A. Charbonnier, S. Rosier-Lees, G. Rowell, E. Brion, B. Rudak, C. B. Rulten, J. Ruppel, V. Sahakian, A. Santangelo, R. Schlickeiser, F. M. Schoeck, R. C. G. Chaves, L. Stawarz, R. Schroeder, U. Schwanke, S. Schwarzburg, J. Brucker, S. Schwemmer, R. Steenkamp, C. Stegmann, G. Superina, P. H. Tam, A. Cheesebrough, P. Brun
The rapidly varying (~10 min timescale) non-thermal X-ray emission observed from Sgr A$^{\star}$ implies that particle acceleration is occuring close to the event horizon of the supermassive black hole. The TeV $\gamma$-ray source HESS J1745-290 is coincident with Sgr A$^{\star}$ and may be closely related to its X-ray emission. Simultaneous X-ray and TeV observations are required to elucidate the relationship between these objects. We report on joint HESS/Chandra observations performed in July 2005, during which an X-ray flare was detected. Despite a factor of $\approx$9 increase in the X-ray flux of Sgr A$^{\star}$, no evidence is found for an increase in the TeV $\gamma$-ray flux from this region. We find that an increase in the $\gamma$-ray flux of a factor of 2 or greater can be excluded at a confidence level of 99%. This finding disfavours scenarios in which the keV and TeV emission are associated with the same population of accelerated particles and in which the bulk of the $\gamma$-ray emission is produced within ~1014 cm (~100 $\,R_{\rm S}$) of the supermassive black hole.



Astronomy & Astrophysics, 2008, 492 (1), pp. L25-L28


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