A Transient Sub-Eddington Black Hole X-ray Binary Candidate in the Dust Lanes of Centaurus A
arXiv:1202.3149 · doi:10.1088/0004-637X/749/2/112
Abstract
We report the discovery of a bright X-ray transient, CXOU J132527.6-430023, in the nearby early-type galaxy NGC 5128. The source was first detected over the course of five Chandra observations in 2007, reaching an unabsorbed outburst luminosity of 1-2*10^38 erg/s in the 0.5-7.0 keV band before returning to quiescence. Such luminosities are possible for both stellar-mass black hole and neutron star X-ray binary transients. Here, we attempt to characterize the nature of the compact object. No counterpart has been detected in the optical or radio sky, but the proximity of the source to the dust lanes allows for the possibility of an obscured companion. The brightness of the source after a >100 fold increase in X-ray flux makes it either the first confirmed transient non-ULX black hole system in outburst to be subject to detailed spectral modeling outside the Local Group, or a bright (>10^38 erg/s) transient neutron star X-ray binary, which are very rare. Such a large increase in flux would appear to lend weight to the view that this is a black hole transient. X-ray spectral fitting of an absorbed power law yielded unphysical photon indices, while the parameters of the best-fit absorbed disc blackbody model are typical of an accreting ~10 Msol black hole in the thermally dominant state.
8 pages, 6 figures, accepted for publication in ApJ
References in corpus (18)
- X-ray Properties of Black-Hole Binaries
- High-energy particle acceleration at the radio-lobe shock of Centaurus A
- The Discovery of Cepheids and a Distance to NGC 5128
- RXTE observations of the first transient Z source XTE J1701-462: shedding new light on mass accretion in luminous neutron star LMXBs
- A giant radio flare from Cygnus X-3 with associated Gamma-ray emission
- New results on particle acceleration in the Centaurus A jet and counterjet from a deep Chandra observation
- Very Broad [O III]4959,5007 Emission from the NGC 4472 Globular Cluster RZ2109 and Implications for the Mass of Its Black Hole X-ray Source
- Low-Mass X-ray Binaries and Globular Clusters in Centaurus A
- Luminosity functions of LMXBs in Centaurus A: globular clusters versus the field
- Deep Chandra Monitoring Observations of NGC 3379: Catalog of Source Properties
- Deep Chandra Monitoring Observations of NGC 4278: Catalog of Source Properties
- Where Centaurus A gets its X-ray knottiness
- CXOM31 J004253.1+411422: The first ultra-luminous X-ray transient in M 31
- Evidence for Non-Hydrostatic Gas Motions in the Hot ISM of Centaurus A
- A Transient Black-Hole Low-Mass X-Ray Binary Candidate in Centaurus A
- The Chandra ACIS Survey of M33 (ChASeM33): Transient X-ray Sources Discovered in M33
- Globular Clusters and X-ray Point Sources in Centaurus A (NGC 5128)
- Three X-ray transients in M31 observed with Swift