Author(s): Aharonian F., Bazer-Bachi A.R., Becherini Y., Boisson C., Borrel V., Brion E., Brun P., Boutelier T., Charbonnier A., Chounet L.-M., Coignet G., Degrange B., Djannati-Ataï A., Dubois F., Dubus G., Espigat P., Farnier C., Feinstein F., Fiasson A., Fontaine G., Gallant Y., Gérard L., Giebels B., Glicenstein J.F., Goret P., Henri G., Jacholkowska A., Khélifi B., Marcowith A., Vasileiadis G.
(Article) Published:
Astronomy & Astrophysics, vol. 492 p.L25-L28 (2008)
Links openAccess full text : 
Ref HAL: in2p3-00348809_v1
Ref Arxiv: 0812.3762
DOI: 10.1051/0004-6361:200810912
Ref. & Cit.: NASA ADS
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27 citations
Abstract:
The rapidly varying (~10 minute 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 gamma-ray source HESS J1745-290 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 H.E.S.S./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 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 ~10^{14} cm (~100 R_S) of the supermassive black hole.
Comments: 5 pages, 2 figures