X-ray transients in the galactic center region

Abstract

In the last 15 years, 6 dedicated observation programs were carried out to monitor ~20 deg around the galactic center for transient activity above a few keV. Transient activity from low-mass X-ray binaries shows a strong preference for this field. Two programs are currently active, with the Wide Field Cameras on BeppoSAX and the Proportional Counter Array on RXTE. The coverage of these programs is fairly extensive, with typical sensitivities of a few mCrab and an angular resolution of a few arcminutes which is better than that of typical all-sky monitor devices. Fifteen transients with peak fluxes above 10 mCrab were discovered with these instruments so far (equivalent to 12 +/- 4 such transients per year over the whole sky), and on top of that BeppoSAX-WFC detected about 2000 X-ray bursts. We summarize some recent results.