A deeper look at the X-ray point source population of NGC 4472

T. D. Joseph, T. J. Maccarone, R. P. Kraft, G. R. Sivakoff

Research output: Contribution to journalArticlepeer-review


In this paper we discuss the X-ray point source population of NGC 4472, an elliptical galaxy in the Virgo cluster. We used recent deep Chandra data combined with archival Chandra data to obtain a 380 ks exposure time. We find 238 X-ray point sources within 3.7 arcmin of the galaxy centre, with a completeness flux, FX, 0.5-2 keV = 6.3 × 10-16 erg s-1 cm-2. Most of these sources are expected to be low-mass X-ray binaries. We finding that, using data from a single galaxy which is both complete and has a large number of objects (~100) below 1038 erg s-1, the X-ray luminosity function is well fitted with a single power-law model. By cross matching our X-ray data with both space based and ground based optical data for NGC 4472, we find that 80 of the 238 sources are in globular clusters. We compare the red and blue globular cluster subpopulations and find red clusters are nearly six times more likely to host an X-ray source than blue clusters. We show that there is evidence that these two subpopulations have significantly different X-ray luminosity distributions. Source catalogues for all X-ray point sources, as well as any corresponding optical data for globular cluster sources, are also presented here.

Original languageEnglish
Pages (from-to)4133-4144
Number of pages12
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - Oct 2017


  • Stars: low mass
  • X-rays: binaries
  • X-rays: individual: NGC 4472


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