The IBIS view of the galactic centre: INTEGRAL’s imager observations simulations

Abstract

The Imager on Board Integral Satellite (IBIS) is the imaging instrument of the INTEGRAL satellite, the hard-X/soft-gamma ray ESA mission to be launched in 2001. It provides diagnostic capabilities of fine imaging (12' FWHM), source identification and spectral sensitivity to both continuum and broad lines over a broad (15 keV-10 MeV) energy range. It has a continuum sensitivity of 2 10 −7 ph cm −2 s −1 at 1 MeV for a 10 6 seconds observation and a spectral resolution better than 7 % at 100 keV and of 6 % at 1 MeV. The imaging capabilities of the IBIS are characterized by the coupling of the above quoted source discrimination capability with a very wide field of view (FOV), namely 9 • × 9 • fully coded, 29 • × 29 • partially coded FOV. We present simulations of IBIS observations of the Galactic Center based on the results of the SIGMA Galactic Center survey. They show the capabilities of this instrument in discriminating between different sources while at the same time monitoring a huge FOV. It will be possible to simultaneously take spectra of all of these sources over the FOV even if the sensitivity decreases out of the fully coded area. It is envisaged that a proper exploitation of both the FOV dimension and the source localization capability of the IBIS will be a key factor in maximizing its scientific output.

Galactic binaries can explain the Fermi Galactic centre excess and 511 keV emission

“…Sky-images are constructed in the energy 491-531 keV, similar to the IBIS analysis of the inner-Galaxy as performed by De Cesare (2011). For the field-of-view (FoV) we consider the fully-coded field-of-view of 9 • × 9 • (note that the larger partially coded field of view is 29 • ×29 • ) (Goldoni et al 1997;Goldwurm et al 2003)). The effective area of IBIS is taken to be A eff = 54.2 cm 2 and the exposure towards the inner-Galaxy T obs = 10 7 s. Finally, we include a term eff = 0.75 to capture the imaging efficiency (De Cesare 2011).…”

The Coma Cluster at γ-ray energies: Multifrequency constraints

“…Observationally upper limits are currently provided by OSSE (Rephaeli et al 1994) and EGRET (Reimer et al 2003). INTEGRAL with its moderate continuum sensitivity 1 permits a chance to detect Coma as a marginally extended source up to a few 100 keV by ISGRI (Goldoni et al 2001). PICsIT and SPI, however, will not be able to detect the Coma cluster given realistic observation times of <10 7 s. The current generation of imaging Cherenkov telescopes (IACTS; Weekes et al 2002), in particular in northern locations, will reach the required sensitivity only if significantly more than 50 h of observation will be accumulated.…”