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Astrophysics

Exception tests the rules

Nature volume 503, pages 477–478 (2013)Cite this article

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Detailed observations of an intermittent ultraluminous X-ray source indicate that its emission is unlikely to be powered by mass accretion onto an intermediate-mass black hole as previously thought. See Letter p.500

Ultraluminous X-ray sources (ULXs) are extragalactic sources of X-rays, powered by black holes, that are not coincident with galactic nuclei and have luminosities greater than 1039 erg per second — roughly the highest luminosity that stellar-mass black holes, which weigh less than about 30 solar masses, should be able to achieve. Many types of X-ray source could fit this definition, and there has been a recent multiplication of ULX types. On page 500 of this issue, Liu et al.1 use an intermittent ULX in the spiral galaxy M 101 — an object that purists might argue is not a 'real' ULX — to show that several aspects of our understanding of ULXs and, indeed, of black-hole formation, may need to be revised.

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Figure 1: The host galaxy of ultraluminous X-ray source M 101 ULX-1.

JIFENG LIU/SDSS

References

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  1. K. D. Kuntz is in the Henry A. Rowland Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA.,

    K. D. Kuntz

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  1. K. D. Kuntz
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Correspondence to K. D. Kuntz.

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Kuntz, K. Exception tests the rules. Nature 503, 477–478 (2013). https://doi.org/10.1038/503477a

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