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Several molecular clouds around the Galactic Centre (GC) emit strong neutral iron fluorescence line at 6.4 keV, as well as hard X‐ray emission up to 100 keV. The origin of this emission has long been a matter of controversy: irradiation by low energy cosmic ray electrons or X‐rays emitted by a nearby flaring source in the central region. A recent evidence for time variability in the iron line intensity that has been detected in the Sgr B2 cloud favors the reflexion scenario. We present here the data obtained after 6 years of INTEGRAL monitoring of the GC. In particular, we show a lightcurve of Sgr B2 that reveals a decrease in the hard X‐ray flux over the last years and discuss its implications. We finally discuss perspectives with Simbol‐X.

Supemovae and their remnants are the main Galactic nucleosynthesis sites and the privileged sources of Galactic cosmic rays. The youngest of such remnants can be studied through two distinct observational features: 44Ti γ‐ray lines and the hard X‐ray nonthermal continuum emission. The former gives unique information on the nucleosynthesis conditions occuring during the first stages of the explosion, while the latter provides clues on acceleration processes at supernova remnant shocks. In this contribution, we present new INTEGRAL results on Tycho, the remnant of a historical supernova, and on G1.9+0.3, which has been recently unveiled as the youngest Galactic supernova remnant. Expectations with Simbol‐X are also addressed.

In this paper, I intend to review our current knowledge on Kepler’s supernova remnant. The observations are discussed with a special emphasis on the inputs they provide to model this remnant. In particular, the X-ray band provides crucial informations and constraints on the origin of Kepler’s SNR, on its evolutionary stage as well as on particle acceleration at the forward and reverse shocks.

The XMM-Newton X-ray observatory pointed the galactic black hole candidate and microquasar GRS 1758-258 in September 2000 for about 10 ks during a program devoted to the scan of the Galactic Center regions. Preliminary results from EPIC MOS camera data are presented here. The data indicate that the source underwent a state transition from its standard low-hard state to an intermediate state. For the first time in this source the ultra-soft component of the accretion disk, which black hole binaries display in intermediate or high-soft states, was clearly detected and measured thanks to the high spectral capabilities of XMM-Newton., Comment: To appear in the Proc. of the Gamma-Ray Astrophysics 2001 Symposium, 4-6 April 2001, Baltimore, Maryland, U.S.A.. American Institute of Physics (AIP) series: 5 pages, 6 PS figures, latex, uses aipproc.cls aipproc.sty