The Open UniversitySkip to content
 

New XMM-Newton Analysis of Three Bright X-Ray Sources in M31 Globular Clusters, Including a New Black Hole Candidate

Barnard, R.; Stiele, H.; Hatzidimitriou, D.; Kong, A. K. H.; Williams, B. F.; Pietsch, W.; Kolb, U. C.; Haberl, F. and Sala, G. (2008). New XMM-Newton Analysis of Three Bright X-Ray Sources in M31 Globular Clusters, Including a New Black Hole Candidate. Astrophysical Journal, 689(2) pp. 1215–1221.

DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1086/592594
Google Scholar: Look up in Google Scholar

Abstract

We present a detailed analysis of three globular cluster X-ray sources in the XMM-Newton extended survey of M31. The X-ray counterpart to the M31 globular cluster Bo 45 (XBo 45) was observed with XMM-Newton on 2006 December 26. Its combined pn+MOS 0.3–10 keV light curve was seen to vary by 10%, and its 0.3–7.0 keV emission spectrum was well described by an absorbed power law with photon index . Its variability and emission is characteristic of low-mass X-ray binaries (LMXBs) in the low-hard state, whether the accretor is a neutron star or black hole. Such behavior is typically observed at luminosities 10% Eddington. However, XBo 45 exhibited this behavior at an unabsorbed, 0.3–10 keV luminosity of erg s−1, or 140% Eddington for a 1.4 neutron star accreting hydrogen. Hence, we identify XBo 45 as a new candidate black hole LMXB. XBo 45 appears to have been consistently bright for 30 years, consistent with theoretical prediction for a globular cluster black hole binary formed via tidal capture. Bo 375 was observed in the 2007 January 2 XMM-Newton observation, and has a two-component spectrum that is typical for a bright neutron star LMXB. Bo 135 was observed in the same field as Bo 45, and could contain either a black hole or a neutron star.

Item Type: Journal Article
Copyright Holders: 2008 The American Astronomical Society
ISSN: 1538-4357
Academic Unit/Department: Science > Physical Sciences
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
eSTEeM
Item ID: 12792
Depositing User: Robin Barnard
Date Deposited: 08 Jan 2009 01:28
Last Modified: 05 Mar 2014 10:27
URI: http://oro.open.ac.uk/id/eprint/12792
Share this page:

Altmetrics

Scopus Citations

Actions (login may be required)

View Item
Report issue / request change

Policies | Disclaimer

© The Open University   + 44 (0)870 333 4340   general-enquiries@open.ac.uk