Near-infrared counterparts of ultraluminous X-ray sources - towards dynamical mass measurements
Abstract
Are ultraluminous X-ray sources powered by stellar or intermediate mass black holes? To answer this question we need reliable mass measurements of these systems. The best way to do this would be to measure the radial velocity curves of the companion stars and thus derive the mass functions for these black holes. This has proven to be very difficult for ULXs because the optical light from these systems is dominated by the accretion disc. However, some ULXs may have red supergiant donor stars, that are intrinsically bright in the near-infrared and may enable us to measure their radial velocity curves in that part of the spectrum. We have conducted a survey of nearby ULXs to search for near-infrared counterparts. Of our 62 targets, 11 have a counterpart that could potentially be a red supergiant (Heida et al. 2014). I will present results of this survey and initial results of our NIR spectroscopic follow-up of several of the sources where we detected a NIR counterpart.
- Publication:
-
AAS/High Energy Astrophysics Division #14
- Pub Date:
- August 2014
- Bibcode:
- 2014HEAD...1440404H