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We have examined X-ray and optical observations of two ultra-luminous X-ray sources, X7 and X10 in NGC4559, using XMM-Newton, Chandra and HST. The UV/X-ray luminosity of X7 exceeds 2.1 × 10 40 erg s −1 in the XMM-Newton observation, and that of X10 is > 1.3×10 40 erg s −1. X7 has both thermal and power-law spectral components, The characteristic temperature(More)
We obtained deep optical imaging of the thermally emitting X-ray bright and radio-quiet isolated neutron star RX J1605.3+3249 with the Subaru telescope in 1999 and 2003. Together with archival HST images acquired in 2001 these data reveal a proper motion of µ = 144.5 ± 13.2 mas/yr. This implies a relatively high spatial velocity and indicates that the star(More)
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(More)
  • C Motch, P Guillout, +6 authors F.-J Zickgraf
  • 1997
We report on optical searches in the error circles of 93 ROSAT survey sources located at low galactic latitudes (|b| < 20 •). These sources were extracted from the ROSAT Galactic Plane Survey using various selection criteria on hardness ratio, X-ray and optical brightness and integrated galactic absorption in the direction of the source. We find optical(More)
We discuss our radio (Australia Telescope Compact Array and Australian Long Baseline Array) and X-ray (XMM-Newton) monitoring observations of the unusual ultraluminous supernova SN 1978K in NGC 1313 at ∼ 25 years after the explosion. SN 1978K is a rare example of a Type IIn supernova that has remained bright enough to have long-term X-ray and radio(More)
We have studied the candidate optical counterparts and the stellar population in the star-forming complex around the bright ULX in the western part of the spiral galaxy NGC 4559, using HST/WFPC2, XMM-Newton/Optical Monitor, and ground-based data. We find that the ULX is located near a small group of OB stars, but is not associated with any massive young(More)
Black-hole accretion states near or above the Eddington luminosity (the point at which radiation force outwards overcomes gravity) are still poorly known because of the rarity of such sources. Ultraluminous X-ray sources are the most luminous class of black hole (L(X) approximately 10(40) erg s(-1)) located outside the nuclei of active galaxies. They are(More)
We have studied an ultraluminous X-ray source (ULX) in NGC 4559 with XMM-Newton, and its peculiar star-forming environment with HST/WFPC2. The X-ray source is one of the brightest in its class (L x ≈ 2 × 10 40 erg s −1). Luminosity and timing arguments suggest a mass ∼ > 50M ⊙ for the accreting black hole. The ULX is located near the rim of a young (age <(More)