Open AccessThe discovery of X‐ray binaries in the Sculptor dwarf spheroidal galaxy
Author(s) -
Maccarone Thomas J.,
Kundu Arunav,
Zepf Stephen E.,
Piro Anthony L.,
Bildsten Lars
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society: letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.067
H-Index - 122
eISSN - 1745-3933
pISSN - 1745-3925
DOI - 10.1111/j.1745-3933.2005.00106.x
Subject(s) - physics , astrophysics , milky way , dwarf spheroidal galaxy , galaxy , astronomy , dwarf galaxy , population , stars , interacting galaxy , demography , sociology
We report the results of a deep Chandra survey of the Sculptor dwarf spheroidal galaxy. We find five X‐ray sources with L X of at least 6 × 10 33 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.