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

Research output: Contribution to journalArticle (Academic Journal)peer-review

19 Citations (Scopus)


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

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