Abstract
We present results of a Chandra survey of the ultraluminous X-ray sources (ULX) in 13 normal galaxies, in which we combine source detection with X-ray flux measurement. 22 ULX were detected, i.e. with L-x > 1 x 10(39) erg s(-1) (L-10) and 39 other sources were detected with L-x > 5 x 10(38) erg s(-1) (L-5). We also use radial intensity profiles to remove extended sources from the sample. The majority of sources are not extended, which for a typical distance constrains the emission region size to less than 50 pc. X-ray colour-colour diagrams and spectral fitting results were examined for indicators of the ULX nature. In the case of the brighter sources, spectral fitting generally requires two-component models. In only a few cases do colour-colour diagrams or spectral fitting provide evidence of a black hole nature. We find no evidence of a correlation with stellar mass, however, there is a strong correlation with star formation as indicated by the 60-mum flux as found in previous studies.
Original language | English |
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Pages (from-to) | 134-148 |
Number of pages | 15 |
Journal | Royal Astronomical Society. Monthly Notices |
Volume | 344 |
DOIs | |
Publication status | Published - 1 Sept 2003 |
Keywords
- X-rays : galaxies
- black hole physics
- binaries : close
- X-rays : stars
- accretion, accretion discs