Optical observations of ultraluminous X-ray sources

Grisé, F.; Pakull, M.; Motch, C.
Bibliographical reference

SF2A-2005: Semaine de l'Astrophysique Francaise, meeting held in Strasbourg, France, June 27 - July 1, 2005, Edited by F. Casoli, T. Contini, J.M. Hameury and L. Pagani. Published by EdP-Sciences, Conference Series, 2005, p. 549

Advertised on:
12
2005
Number of authors
3
IAC number of authors
0
Citations
1
Refereed citations
1
Description
We report recent observational results of some ULXs collected with the 8.2m Subaru and with the ESO VLT telescopes. These observations have provided important information on the (inter-) stellar environments and have allowed to detect the optical counterparts of several ULXs. In two cases spectroscopic observations show stellar HeIIλ4686 optical emission reminiscent of X-ray heated accretion discs. This confirms the identification and provides independent evidence for an extremely high X-ray luminosity, thus excluding strong beaming effects. This opens the possibility to directly determine the masses of the binary component and to confirm or refute the existence of intermediate mass black holes (IMBHs).