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

F. Aharonian, G. A. Akhperjanian, U. Barres De Almeida, R. A. Bazer-Bachi, Y. Becherini, B. Behera, W. Benbow, K. Bernlöhr, C. Boisson, A. Bochow, V. Borrel, I. Braun, E. Brion, J. Brucker, P. Brun, R. Bühler, T. Bulik, I. Büsching, T. Boutelier, S. CarriganM. P. Chadwick, A. Charbonnier, C. G R Chaves, A. Cheesebrough, L. M. Chounet, C. A. Clapson, G. Coignet, M. Dalton, B. Degrange, C. Deil, J. H. Dickinson, A. Djannati-Ataï, W. Domainko, O'C L. Drury, F. Dubois, G. Dubus, J. Dyks, M. Dyrda, K. Egberts, D. Emmanoulopoulos, P. Espigat, C. Farnier, F. Feinstein, A. Fiasson, A. Förster, G. Fontaine, M. Füßling, S. Gabici, A. Y. Gallant, L. Gérard, B. Giebels, F. J. Glicenstein, B. Glück, P. Goret, C. Hadjichristidis, D. Hauser, M. Hauser, S. Heinz, G. Heinzelmann, G. Henri, G. Hermann, A. J. Hinton, A. Hoffmann, W. Hofmann, M. Holleran, S. Hoppe, D. Horns, A. Jacholkowska, C. O. De Jager, I. Jung, K. Katarzyński, S. Kaufmann, E. Kendziorra, M. Kerschhaggl, D. Khangulyan, B. Khélifi, D. Keogh, Nu Komin, K. Kosack, G. Lamanna, J. P. Lenain, T. Lohse, V. Marandon, M. J. Martin, O. Martineau-Huynh, A. Marcowith, D. Maurin, J. L T McComb, C. M. Medina, R. Moderski, E. Moulin, M. Naumann-Godo, M. De Naurois, D. Nedbal, D. Nekrassov, J. Niemiec, J. S. Nolan, S. Ohm, J. F. Olive, E. De Oña Wilhelmi, J. Orford, L. Osborne, M. Ostrowski, M. Panter, G. Pedaletti, G. Pelletier, P. O. Petrucci, S. Pita, G. Pühlhofer, M. Punch, A. Quirrenbach, C. B. Raubenheimer, M. Raue, M. S. Rayner, M. Renaud, F. Rieger, J. Ripken, L. Rob, S. Rosier-Lees, G. Rowell, B. Rudak, B. C. Rulten, J. Ruppel, V. Sahakian, A. Santangelo, R. Schlickeiser, M. F. Schöck, R. Schröder, U. Schwanke, S. Schwarzburg, S. Schwemmer, A. Shalchi, L. J. Skilton, H. Sol, D. Spangler, Å Stawarz, R. Steenkamp, C. Stegmann, G. Superina, H. Tam, J. P. Tavernet, R. Terrier, O. Tibolla, C. Van Eldik, G. Vasileiadis, C. Venter, P. J. Vialle, P. Vincent, M. Vivier, J. H. Völk, F. Volpe, J. S. Wagner, M. Ward, A. A. Zdziarski, A. Zech

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26 Scopus citations


The rapidly varying (~10 min timescale) non-thermal X-ray emission observed from Sgr A implies that particle acceleration is occuring close to the event horizon of the supermassive black hole. The TeV γ-ray source HESSJ1745-290 is coincident with Sgr A* 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 ≈9 increase in the X-ray flux of Sgr A*, no evidence is found for an increase in the TeV γ-ray flux from this region. We find that an increase in the γ-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 γ-ray emission is produced within ∼ cm (∼100 Rs) of the supermassive black hole.

Original languageEnglish (US)
Pages (from-to)L25-L28
JournalAstronomy and Astrophysics
Issue number1
StatePublished - Dec 1 2008


  • Gamma rays: observations
  • X-rays: individuals: Sgr A

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