A Transient Black-Hole Low-Mass X-Ray Binary Candidate in Centaurus A
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, Nicola; Croston, J.H.; Harris, W.F.; Jones, C.; Murray, S.S.; Raychaudhury, S.; Woodley, K.A.; Worrall, D.M.
Citation: 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 , Croston , J H , Harris , W F , 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 , vol 677 , pp. L27-L30 .
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 article can be found at: http://www.iop.org/EJ/journal/apjl Copyright American Astronomical Society DOI: 10.1086/587960 [Full text of this article is not available in the UHRA]