Near-infrared counterparts to the galactic bulge survey x-ray source population

S. Greiss, D. Steeghs, P. G. Jonker, M. A.P. Torres, T. J. Maccarone, R. I. Hynes, C. T. Britt, G. Nelemans, B. T. Gänsicke

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


We report on the near-infrared matches, drawn from three surveys, to the 1640 unique X-ray sources detected by Chandra in the Galactic Bulge Survey (GBS). This survey targets faint X-ray sources in the bulge, with a particular focus on accreting compact objects. We present all viable counterpart candidates and associate a false alarm probability (FAP) to each near-infrared match in order to identify the most likely counterparts. The FAP takes into account a statistical study involving a chance alignment test, as well as considering the positional accuracy of the individual X-ray sources. We find that although the star density in the bulge is very high, ̃90 per cent of our sources have an FAP <10 per cent, indicating that for most X-ray sources, viable near-infrared counterparts candidates can be identified. In addition to the FAP, we provide positional and photometric information for candidate counterparts to ̃95 per cent of the GBS X-ray sources. This information in combination with optical photometry, spectroscopy and variability constraints will be crucial to characterize and classify secure counterparts.

Original languageEnglish
Pages (from-to)2839-2852
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - Mar 2014


  • Infrared: stars
  • Surveys
  • X-rays: binaries
  • X-rays: stars


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