Low-mass X-ray binaries and globular clusters in centaurus A

Andres Jordan*, Gregory R. Sivakoff, Dean E. McLaughlin, John P. Blakeslee, Daniel A. Evans, Ralph P. Kraft, Martin J. Hardcastle, Eric W. Peng, Patrick Cote, Judith H. Croston, Adrienne M. Juett, Dante Minniti, Somak Raychaudhury, Craig L. Sarazin, Diana M. Worrall, William E. Harris, Kristin A. Woodley, Mark Birkinshaw, Nicola J. Brassington, William R. FormanChristine Jones, Stephen S. Murray

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

40 Citations (Scopus)


We present results of Hubble Space Telescope and Chandra X-Ray Observatory observations of globular clusters (GCs) and low-mass X-ray binaries (LMXBs) in the central regions of Centaurus A. Out of 440 GC candidates, we find 41 host X-ray point sources that are most likely LMXBs. We fit King models to our GC candidates in order to measure their structural parameters. We find that GCs that host LMXBs are denser and more compact and have higher encounter rates and concentrations than the GC population as a whole. We show that the higher concentrations and masses are a consequence of the dependence of LMXB incidence on central density and size plus the general trend for denser GCs to have higher masses and concentrations. We conclude that neither concentration nor mass is a fundamental variable in determining the presence of LMXBs in GCs and that the more fundamental parameters relate to central density and size.

Original languageEnglish
Pages (from-to)L117-L120
Number of pages4
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 20 Dec 2007


  • galaxies : elliptical and lenticular, cD
  • globular clusters : general
  • X-rays : binaries
  • NGC 5128
  • NGC-5128


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