Tracking spectral variability with luminosity in the ultraluminous state
Abstract
A substantial body of evidence suggests that most ultraluminous X-ray sources (ULXs) are stellar remnant black holes accreting at super-Eddington rates, in a new `ultraluminous' accretion state. Little is known of the astrophysics of this putative state to date. Gladstone et al. (2009) propose a sequence of three spectral regimes that ULXs may progress through as their accretion rate increases; but no evidence for this progression from an individual source has yet been seen. Here, we propose three observations of a highly variable ULX in NGC 5907, triggered at different flux levels by Swift monitoring data. These will investigate whether large amplitude luminosity variation in a ULX is accompanied by transitions through these ultraluminous state regimes.
- Publication:
-
XMM-Newton Proposal
- Pub Date:
- October 2010
- Bibcode:
- 2010xmm..prop..167S
- Keywords:
-
- White Dwarf Binaries;
- Neutron Star Binaries;
- Cataclysmic Variables;
- ULXs;
- Black Holes;
- NGC 5907 ULX;
- NGC 5907 ULX