Searching for IMBH candidates among Ultraluminous X-ray Sources
Abstract
A sub-sample of bright Ultraluminous X-ray Sources (L_X~(1-5)x10^40 erg/s)shows peculiar powerlaw like spectra, with no high energy turn-off andshort-term variability at the level of ~10%. These sources might hostIntermediate Mass Black Holes (IMBHs) in a low/hard state, althoughtheir apparently flat spectral shape may be the effect of poor countingstatistics. Here we propose simultaneous, deep XMM- Newton and NuSTARobservations of four such objects to find evidence either of the X-rayproperties (powerlaw spectra and short term variability) that shouldcharacterize sub-Eddington accretion onto an IMBH or of the characteristicspectral curvature of the `Ultraluminous state'.
- Publication:
-
XMM-Newton Proposal
- Pub Date:
- October 2015
- Bibcode:
- 2015xmm..prop..173P