Aharonian, F.Büsching, I.De Jager, O.C.Holleran, M.Raubenheimer, B.C.Venter, C.H.E.S.S. Collaboration2010-01-182010-01-182008Aharonian, F. et al. 2008. Simultaneous HESS and Chandra observations of Sagitarius A* during an X-ray flare. Astronomy & astrophysics, 492(1):L25-L28. [https://doi.org/10.1051/0004-6361:200810912]0004-63611432-0746 (Online)http://hdl.handle.net/10394/2750https://doi.org/10.1051/0004-6361:200810912http://www.aanda.org/articles/aa/pdf/2008/46/aa10912-08.pdfThe 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 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 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 ~1014 cm (~100) of the supermassive black holeenX-rays: individuals: Sgr A*gamma rays: observationsArticle