A transient black hole low-mass X-ray binary candidate in Centaurus A

G. R. Sivakoff*, R. P. Kraft, A. Jordan, A. M. Juett, D. A. Evans, W. R. Forman, M. J. Hardcastle, C. L. Sarazin, M. Birkinshaw, N. J. Brassington, J. H. Croston, W. E. Harris, C. Jones, S. S. Murray, S. Raychaudhury, K. A. Woodley, D. M. Worrall

*Corresponding author for this work

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We report the discovery of a bright transient X-ray source, CXOU J132518.2-430304, toward Centaurus A (Cen A) using six new Chandra X-Ray Observatory observations in 2007 March-May. Between 2003 and 2007, its flux has increased by a factor of > 770. The source is likely a low-mass X-ray binary in Cen A with unabsorbed 0.3-10 keV band luminosities of (2-3) x 10(39)ergs s(-1) and a transition from the steep-power-law state to the thermal state during our observations. CXOU J132518.2-430304 is the most luminous X-ray source in an early-type galaxy with extensive timing information that reveals transience and a spectral state transition. Combined with its luminosity, these properties make this source one of the strongest candidates to date for containing a stellar-mass black hole in an early-type galaxy. Unless this outburst lasts many years, the rate of luminous transients in Cen A is anomalously high compared to other early-type galaxies.

Original languageEnglish
Pages (from-to)L27-L30
Number of pages4
JournalAstrophysical Journal
Issue number1
Publication statusPublished - 10 Apr 2008


  • binaries : close
  • galaxies : elliptical and lenticular
  • cD galaxies : individual (Centaurus A, NGC 5128)
  • X-rays : binaries
  • M31

Cite this

Sivakoff, G. R., Kraft, R. P., Jordan, A., Juett, A. M., Evans, D. A., Forman, W. R., Hardcastle, M. J., Sarazin, C. L., Birkinshaw, M., Brassington, N. J., Croston, J. H., Harris, W. E., Jones, C., Murray, S. S., Raychaudhury, S., Woodley, K. A., & Worrall, D. M. (2008). A transient black hole low-mass X-ray binary candidate in Centaurus A. Astrophysical Journal, 677(1), L27-L30.