The INTEGRAL View of the Galactic Nucleus

A. Goldwurm, G. Belanger, P. Goldoni, J. Paul, R. Terrier, M. Falanga, P. Ubertini, A. Bazzano, M. Del Santo, C. Winkler, A. N. Parmar, E. Kuulkers, K. Ebisawa, J.P. Roques, G. Skinner, N. Lund, F. Melia, F. Yusef-Zadeh

Paper: ESA-SP, 2004, 5th INTEGRAL Conf. Proc., in press

EPrint Server: astro-ph/0407264

We present the preliminary results of the observational campaign performed in 2003 to study the Galactic nucleus with INTEGRAL. The mosaicked images obtained with the IBIS/ISGRI coded aperture instrument in the energy range above 20 keV, give a yet unseen view of the high-energy sources of this region in hard X- and gamma-rays, with an angular resolution of 12'. We report on the discovery of a source, IGR J17456-2901, compatible with the instrument's point spread function and coincident with the Galactic nucleus \sgra to within 0.9'. The source is visible up to 60-80 keV with a 20-100 keV luminosity at 8 kpc of 3 * 10³⁵ erg s^-1. Although we cannot unequivocally associate the new INTEGRAL source to the Galactic Nucleus, this is the first report of significant hard X-ray emission from within the inner 10' of the Galaxy and a contribution from the galactic center supermassive black hole itself cannot be excluded. Here we discuss the results obtained and the perspectives for future observations of the Galactic nucleus with INTEGRAL and other observatories.