The Open UniversitySkip to content

A second black hole candidate in a M31 globular cluster is identified with XMM-Newton

Barnard, R. and Kolb, U. (2009). A second black hole candidate in a M31 globular cluster is identified with XMM-Newton. Monthly Notices of the Royal Astronomical Society, 397 L92-L95.

DOI (Digital Object Identifier) Link:
Google Scholar: Look up in Google Scholar


We use arguments developed in previous work to identify a second black hole candidate associated with an M31 globular cluster (GC), Bo 144, on the basis of X-ray spectral and timing properties. The 2002 XMM–Newton observation of the associated X-ray source (hereafter XBo 144) revealed behaviour that is common to all low-mass X-ray binaries (LMXBs) in the low-hard state. Studies have shown that neutron star LMXBs exhibit this behaviour at 0.01–1000 keV luminosities ≤10 per cent of the Eddington limit (LEdd). However, the unabsorbed 0.3–10 keV luminosity of XBo 144 was ~0.30 LEdd for a 1.4 M neutron star, and the 0.01–1000 keV luminosity is expected to be ≳3–7 times higher. We therefore identify XBo 144 as a black hole candidate. Furthermore, it is the second black hole candidate to be consistent with formation via tidal capture of a main sequence donor in a GC; such systems were previously thought non-existent, because the donor was thought to be disrupted during the capture process.

Item Type: Journal Item
Copyright Holders: 2009 The Authors
ISSN: 1365-2966
Project Funding Details:
Funded Project NameProject IDFunding Body
Not SetNot SetSTFC (Science & Technology Facilities Council)
Extra Information: Please note: not all the mathematical symbols used in the abstract can be displayed
Keywords: black hole physics; galaxies: individual: M31; X-rays: binaries; X-rays: general
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Related URLs:
Item ID: 24409
Depositing User: Ulrich Kolb
Date Deposited: 03 Nov 2010 12:59
Last Modified: 07 Dec 2018 09:43
Share this page:


Altmetrics from Altmetric

Citations from Dimensions

Actions (login may be required)

Policies | Disclaimer

© The Open University   contact the OU