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Astronomy Department Faculty Publication Series
* binaries: general; * ISM: bubbles; * galaxies: individual: M81; * X-rays: galaxies
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Full-Text Articles in Physical Sciences and Mathematics
Ultraluminous X-Ray Source 1e 0953.8+6918 (M81 X-9): An Intermediate-Mass Black Hole Candidate And Its Environs, Qd Wang
Astronomy Department Faculty Publication Series
We present a ROSAT and ASCA study of the Einstein source X-9 and its relation to a shock-heated shell-like optical nebula in a tidal arm of the M81 group of interacting galaxies. Our ASCA observation of the source shows a flat and featureless X-ray spectrum well described by a multicolour disc blackbody model. The source most likely represents an optically thick accretion disc around an intermediate-mass black hole (M∼102 M⊙) in its high/soft state, similar to other variable ultraluminous X-ray sources observed in nearby disc galaxies. Using constraints derived from both the innermost stable orbit …