Bibcode
Grise, Fabien; Kaaret, P.; Corbel, S.; Feng, H.; Cseh, D.; Tao, L.; Pakull, M.; Motch, C.
Referencia bibliográfica
American Astronomical Society, HEAD meeting #12, #13.23
Advertised on:
9
2011
Número de citas
0
Número de citas referidas
0
Descripción
After a decade of intense studies using the latest X-ray and optical
telescopes, the nature of ultraluminous X-ray sources (ULXs) is still
largely unknown. No definitive answer has emerged on the question of the
mass of the black hole powering these objects (intermediate-mass or
supercritical stellar-mass?). Further, we lack even basic knowledge
about the binary systems and the companion stars. We will review the
properties of the optical counterparts of these systems, from where most
properties can be derived. Among the burning issues are: what is the
mass donor in these systems? Are they giant/supergiant stars or
main-sequence stars? What is the donor mass? Is the optical light from
the companion stars or dominated by the accretion disk? We will present
new results from recent HST, Chandra, and VLT observations of ULXs
addressing these questions.