Aharonian, F.Akhperjanian, A.Barres de Almaida, U.Bazer-Bachi, A.Becherini, Y.Behera, B.Benbow, W.Bernlohr, K.Boisson, C.Bochow, A.Borrel, V.Braun, I.Brion, E.Brucker, J.Brun, P.Buhler, R.Bulik, T.Busching, I.Boutelier, T.Carrigan, S.et al.2009-09-092009-09-092008Astronomy and Astrophysics: a European journal, 2008; 492(1):L25-L280004-63611432-0746http://hdl.handle.net/2440/50810Copyright © ESO 2008The 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 RS) of the supermassive black hole.enCopyright © ESO 2008gamma rays: observationsX-rays: individuals: Sgr A*Journal article002008405910.1051/0004-6361:2008109120002612531000072-s2.0-5724911162940976Rowell, G. [0000-0002-9516-1581]