Supergiant Fast X-ray transients from INTEGRAL to NuSTAR
Abstract
Supergiant Fast X-ray transients are a new subclass of High Mass X-ray Binaries that have been extensively observed in the hard X-rays by INTEGRAL and Swift. Monitoring campaigns by the Swift XRT during 2006-2009 have established that these sources spend a significant fraction of their time in a low intensity (~10^34 erg/s) state, characterized by high variability (flaring on the time scale of minutes/hours) and hard spectra. These sources are quite difficult to detect due to the short time scale of the flares, therefore it is possible that a high number of them exist in the Galaxy, most probably populating those regions known to contain a high number of absorbed HMXBs. Therefore, it is expected that a significant number could be seen by NuSTAR in the low intensity state during its planned surveys dedicated to studying regions with a high density of HMXBs (e.g., the Norma region). NuSTAR could also observe SFXT outbursts from sources with periodic outbursts and cyclotron lines from both the outburst and low state.
- Publication:
-
39th COSPAR Scientific Assembly
- Pub Date:
- July 2012
- Bibcode:
- 2012cosp...39.1339N