Exploring ultraluminous X-ray sources using the optical regime
Abstract
Ultraluminous X-ray sources (ULXs) are extragalactic objects located outside the nucleus of their host galaxy, with luminosities >10^39 erg/s. Such high luminosities are in excess of the Eddington limit for a black hole that is about 10 times the mass of our Sun (MSun). ULXs have long been touted as evidence of intermediate mass black holes (MBH = 10^2-10^5 MSun), which are thought to be the building blacks of supermassive black holes. The alternative is that ULXs could be stellar mass (< 100 MSun) black holes accreting at extreme rates, which could explain the rapid growth of super-massive black holes in the early universe. Either option has important cosmological implications, and as a result, mass measurements of these black holes have been a topic of intense interest. Here we present optical analysis of these exotic sources, designed to identify and constrain the companion stars to these black holes. We discuss results from the imaging analysis of 33 nearby ULXs using data from Chandra and the Hubble Space Telescope. We will also present findings from spectroscopic analysis of both pilot and multi-epoch data from 3 of these sources using the Gemini Observatory. By combing this information, we will summarize the implications this work has on both the nature of black holes and companion stars in these systems.
- Publication:
-
11th Hellenic Astronomical Conference
- Pub Date:
- September 2013
- Bibcode:
- 2013hell.confR..23G