Title: Measuring the High Energy Emission of the Galactic Bulge Black Hole X-ray Novae in outburst


Proposal ID: 0120118
Subject category: Compact Object
Principal investigator: Goldwurm
Institute: CEA

Abstract

We propose INTEGRAL ToO follow up observations of new Black Hole (BH) X-ray Novae (XN) detected in outburst in the direction of the Galactic Bulge and which are not subject to guaranteed time ToO observations.In the sky region within 10 degrees from the Galactic Center we expect to observe several (at least 2) faint XN in outburst during the first year of the INTEGRAL mission which will probably not fulfill the triggering criteria for Core Program ToO observations. INTEGRAL however, thanks to its high sensitivity and angular resolution, offer a unique possibility to study these sources, since they are mostly far objects which suffer of large absorption in a very confused region of the sky, where previous low energy and/or non imaging instruments could not provide detailed results. While part of the outburst may be observed by INTEGRAL during the scan in the GCDE survey, a 2 days long pointed INTEGRAL ToO observation planned during the outburst peak in optimum condition of signal to noise will provide a sufficiently detailed spectrum over the 3-700 keV energy band to determine the spectral state of the source and study the relative contribution of ultra-soft, reflection and hard components correlating them to variability properties. In particular this observation will allow to search for the rare and variable high energy emission lines of the type of those detected around 500 keV by SIGMA during the peak of Nova Muscae 1991 in a sample of XN larger than the one covered by the Core Program. We will also carry out correlated multiwavelength observations with ground based observatories which will provide radio/optical data essential to the astrophysical interpretation of the high energy results and in specific we will search for correlation between radio emission and line features. Our ToO observations will optimize the observing strategy of INTEGRAL for the study of BH binaries and thus the scientific return of the mission in one of its major scientific areas.