Ultraluminous X-ray Sources: Bubbles and Optical Counterparts

Abstract

Optical studies of ultraluminous X-ray sources (ULX) in nearby galaxies have turned out to be instrumental in discriminating between various models including the much advertised intermediate mass black hole hypothesis and various beaming scenarios. Here we report on ESO VLT and SUBARU observations of ULX that have revealed the parent stellar clusters with ages of some 60 million years in two cases. Thus we are able to derive upper limits of about 8 M_sun for the mass donors in these systems. The optical counterparts are dominated by X-ray heated accretion disks, and the discovery of the HeII4686 emission line now allows to derive dynamical masses in these systems. Apparent radial velocity variations of 300 km/s have been detected in NGC 1313 X-2 which, if confirmed by further observations, would exclude the presence of IMBH in these systems.

4 pages, to appear in the proceedings of IAU Symposium 230, "Populations of High Energy Sources in Galaxies", Dublin, 15-19 Aug 2005

Cited by in corpus (19)

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• Optical studies of the ultraluminous X-ray source NGC1313 X-2
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• X-ray and optical variability of the ultraluminous X-ray source NGC 1313 X-2
• MUSE spectroscopy of the ULX NGC 1313 X-1: a shock-ionised bubble, an X-ray photoionised nebula, and two supernova remnants
• NIR Counterparts to ULXs (III): Completing the photometric survey and selected spectroscopic results
• The ultraluminous X-ray source bubble in NGC 5585
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• Wind-powered ultraluminous X-ray sources
• Average bolometric corrections and optical to X-ray flux measurements as a function of accretion rate for X-ray binaries
• Two Optical Counterpart Candidates of M82-X1 from HST Observations
• Modelling multiwavelength emission of Ultra-luminous X-ray Sources accreting above the Eddington limit
• The metallicity of the nebula surrounding the ultra-luminous X-ray source NGC 1313 X-2
• Ghost in the Shell: Evidence for Past AGN Activities in NGC 5195 from a Newly Discovered large-scale Ionized Structure
• The onset of General Relativity: Gravitationally redshifted emission lines