Spectral Properties of X-Ray Binaries in Centaurus A

Mark J. Burke, Somak Raychaudhury, Ralph P. Kraft, Thomas Maccarone, Eighteen Other Authors

Research output: Contribution to journalArticlepeer-review


We present a spectral investigation of X-ray binaries (XBs) in NGC 5128 (Cen A), using six 100 ks Chandra observations taken over two months in 2007. We divide our sample into thermally and non-thermally dominated states based on the behavior of the fitted absorption column N H, and present the spectral parameters of sources with Lx >~ 2 × 1037 erg s-1. The majority of sources are consistent with being neutron star low-mass X-ray binaries (NS LMXBs) and we identify three transient black hole (BH) LMXB candidates coincident with the dust lane, which is the remnant of a small late-type galaxy. Our results also provide tentative support for the apparent "gap" in the mass distribution of compact objects between ~2-5 M ⊙. We propose that BH LMXBs are preferentially found in the dust lane, and suggest this is because of the younger stellar population. The majority (~70%-80%) of potential Roche lobe filling donors in the Cen A halo are >~ 12 Gyr old, while BH LMXBs require donors >~ 1 M ⊙ to
Original languageEnglish
Pages (from-to)88
JournalAstrophysical Journal
StatePublished - Apr 2013


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