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, Nicola Brassington, J.H. Croston, W.F. Harris, C. Jones, S.S. Murray, S. Raychaudhury, K.A. Woodley, D.M. Worrall

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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) × 1039ergs 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
JournalThe Astrophysical Journal
Publication statusPublished - 2008


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