THE BIRTH OF AN ULTRALUMINOUS X-RAY SOURCE IN M83
- International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia)
- The Henry A. Rowland Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218 (United States)
- Department of Physics, Middlebury College, Middlebury, VT 05753 (United States)
- Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
A previously undetected (L{sub X} < 10{sup 36} erg s{sup -1}) source in the strongly star-forming galaxy M83 entered an ultraluminous state between 2009 August and 2010 December. It was first seen with Chandra on 2010 December 23 at L{sub X} Almost-Equal-To 4 Multiplication-Sign 10{sup 39} erg s{sup -1} and has remained ultraluminous through our most recent observations in 2011 December, with typical flux variation of a factor of two. The spectrum is well fitted by a combination of absorbed power-law and disk blackbody models. While the relative contributions of the models vary with time, we have seen no evidence for a canonical state transition. The luminosity and spectral properties are consistent with accretion powered by a black hole with M{sub BH} Almost-Equal-To 40-100 M{sub Sun }. In 2011 July we found a luminous, blue optical counterpart that had not been seen in deep Hubble Space Telescope observations obtained in 2009 August. These optical observations suggest that the donor star is a low-mass star undergoing Roche lobe overflow, and that the blue optical emission seen during the outburst is coming from an irradiated accretion disk. This source shows that ultraluminous X-ray sources (ULXs) with low-mass companions are an important component of the ULX population in star-forming galaxies and provides further evidence that the blue optical counterparts of some ULXs need not indicate a young, high-mass companion, but rather that they may indicate X-ray reprocessing.
- OSTI ID:
- 22034489
- Journal Information:
- Astrophysical Journal, Vol. 750, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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