Résumé du preprint Irfu-09-162

Irfu-09-162
Spectrum and variability of the Galactic center VHE gamma-ray source HESS J1745-290
M. Vivier
For the first time, long-term (2004-2006) monitoring is reported for the TeV-bright Galactic center source HESS J1745-290. The association of this source with Sgr A East is definitively ruled out, but Sgr A* and the SNR plus pulsar wind nebula G359.95 0.04 remain viable candidates. The monitoring reported here shows that the spectrum and flux from the TeV source remain constant. There is no evidence of the QPOs or flaring reported from Sgr A* in other energy bands, but diffusing protons could account for the observed VHE spectrum. If the PWN is not contributing to the signal, the variations of Sgr A* must be substantially different at TeV than at lower energies, but it could contribute at least a portion of the observed flux.