Low mass X-ray binaries and black holes in globular clusters

Arunav Kundu, Thomas J. Maccarone, Stephen E. Zepf, I. Chun Shih, Katherine L. Rhode

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Studies of nearby galaxies reveal that roughly half of their low mass X-ray binary (LMXB) populations are associated with globular clusters (GCs). We have established that the LMXB hosting frequency is correlated with various GC properties such as mass and metallicity. While the X-ray luminosities of a few of the brightest LMXBs in GCs is consistent with the accreting object being a black hole (BH), the only definitive way of distinguishing between a black hole and multiple superposed sources in a GC is to detect variability. We have discovered just a variable 4 × 1039 erg s-1 black hole X-ray binary in a low metallicity globular cluster in the halo of NGC 4472. The change in the X-ray spectrum between the bright and faint epochs indicates that the luminosity variation is due to eclipsing by a warped accretion disk. The optical spectrum of this source also reveals strong, broad, [O III] λ5007 and [O III] λ4959 emission. An analysis of the X-ray spectrum indicates that the [O III] lines are produced by the photoionization of a wind driven by a stellar mass black hole accreting mass at or above its Eddington luminosity. As it is dynamically implausible to form an accreting stellar mass BH system in a GC with an intermediate mass BH it appears that this massive cluster does not harbor an intermediate mass BH. The inferred mass of this BH falls well below the extrapolation of the well known M BH-σ and MBH-MStellar to this GC. Therefore our analysis suggests that not all old, metal poor stellar systems form black holes consistent with these relations which have been established for much more massive stellar systems.

Original languageEnglish
Title of host publicationObs. Evid. for Black Holes in the Universe - Proc. of the 2nd Kolkata Conf. on Obs. Evid. for Black Holes in the Universe, Kolkata, India, 10-15 Febr. 2008 and the Satell. Meet. on Black Holes, ...
Pages225-230
Number of pages6
DOIs
StatePublished - 2008
Event2nd Kolkata Conference on Observational Evidence for Black Holes in the Universe and the Satellite Meeting on Black Holes, Neutron Stars, and Gamma-Ray Bursts - Kolkata, India
Duration: Feb 10 2008Feb 17 2008

Publication series

NameAIP Conference Proceedings
Volume1053
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Conference

Conference2nd Kolkata Conference on Observational Evidence for Black Holes in the Universe and the Satellite Meeting on Black Holes, Neutron Stars, and Gamma-Ray Bursts
CountryIndia
CityKolkata
Period02/10/0802/17/08

Keywords

  • Black holes
  • Globular clusters
  • X-ray binaries

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