A Spectroscopic Search for High Mass X-ray Binaries in M31
  We present new optical spectroscopy of 20 candidate counterparts of 17 X-ray
sources in the direction of the M31 disc. By comparing the X-ray catalogue from
the XMM-Newton survey of M31 with star catalogues from the Local Group Galaxy
Survey, we chose counterpart candidates based on optical colour and X-ray
hardness. We have discovered 17 counterpart candidates with spectra containing
stellar features. Eight of these are early-type stars of O or B type in M31,
with hard X-ray spectra, making them good HMXB candidates. Three of these eight
exhibit emission lines, which we consider to be the strongest HMXB candidates.
In addition, our spectra reveal two likely Galactic cataclysmic variables, one
foreground M star, two probable LMXBs related to M31 globular clusters, one
emission line region with an embedded Wolf-Rayet star, and one newly-discovered
supernova remnant. Finally, two of the sources have stellar spectra with no
features indicative of association with an X-ray source.
