Extreme ULXs revisited: spectral state changes as a diagnostic of IMBHs
Abstract
Intermediate-mass black holes (IMBHs) are predicted to have formed throughout cosmic history, and to have seeded supermassive black holes; yet we still have no clear dynamical evidence for any such object. However, recent observations of the most luminous of the ultraluminous X-ray sources (ULXs) are showing increasing evidence for IMBHs, most notable of which is the apparent sub-Eddington state transitions shown by ESO 243-49 HLX-1. Here, we propose EPIC ToOs, triggered from Swift monitoring, for four extreme luminosity ULXs that have observational properties consistent with the hard state for an IMBH. We will use these to search for sub-Eddington state transitions, that may serve as a smoking gun for the presence of an IMBH in these objects.
- Publication:
-
XMM-Newton Proposal
- Pub Date:
- October 2013
- Bibcode:
- 2013xmm..prop...72R
- Keywords:
-
- White Dwarf Binaries;
- Neutron Star Binaries;
- Cataclysmic Variables;
- ULXs;
- Black Holes;
- 2XMM J024025.6-;
- 2XMM J134404.1-;
- 2XMM J230457.6+;
- 2XMM J121856.1+