The discovery of X-ray binaries in the Sculptor dwarf spheroidal galaxy

Thomas J. Maccarone, Arunav Kundu, Stephen E. Zepf, Anthony L. Piro, Lars Bildsten

Research output: Contribution to journalLetter

22 Scopus citations

Abstract

We report the results of a deep Chandra survey of the Sculptor dwarf spheroidal galaxy. We find five X-ray sources with LX of at least 6 × 1033 erg s-1 with optical counterparts establishing them as members of Sculptor. These X-ray luminosities indicate that these sources are X-ray binaries, as no other known class of Galactic point sources can reach 0.5-8 keV luminosities this high. Finding these systems proves definitively that such objects can exist in an old stellar population without stellar collisions. Three of these objects have highly evolved optical counterparts (giants or horizontal branch stars), as do three other sources whose X-ray luminosities are in the range which includes both quiescent low-mass X-ray binaries and the brightest magnetic cataclysmic variables. We predict that large area surveys of the Milky Way should also turn up large numbers of quiescent X-ray binaries.

Original languageEnglish
Pages (from-to)L61-L65
JournalMonthly Notices of the Royal Astronomical Society: Letters
Volume364
Issue number1
DOIs
StatePublished - Nov 2005

Keywords

  • Galaxies: individual: sculptor dwarf spheroidal
  • Stars: binaries: close
  • Stars: population II
  • Stellar dynamics
  • X-rays: binaries
  • X-rays: galaxies

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