Normal galaxies in the XMM-Newton fields. X-rays as a star formation
  indicator
  Context: We use the first XMM serendipitous source catalogue (1XMM) to
compile a sample of normal X-ray galaxies
  Aims: We seek to expand the database of X-ray selected normal galaxies at
intermediate redshifts and examine the relation between X-ray emission and star
formation for late-type systems
  Methods: The candidates are selected based on their X-ray (soft spectra),
X-ray to optical [log(fx/fo)<-2] and optical (extended sources) properties. 44
candidates are found and 35 are spectroscopically observed with the Australian
National University's 2.3m telescope to examine their nature.
  Results: Of the 35 sources observed, 2 are AGN, 11 emission line galaxies, 12
absorption line galaxies, 6 have featureless spectra while 4 are associated
with Galactic stars. We combine our emission line sample with earlier works
forming the most comprehensive X-ray selected galaxy sample for the study of
the X-ray luminosity to the Halpha luminosity - a well-calibrated
star-formation indicator - relation.
  Conclusions: We find that the X-ray luminosity strongly correlates with the
Halpha luminosity, suggesting that the X-rays efficiently trace the
star-formation.
