A stellar census in globular clusters with MUSE: A spectral catalogue of
  emission-line sources
  Globular clusters produce many exotic stars due to a much higher frequency of
dynamical interactions in their dense stellar environments. Some of these
objects were observed together with several hundred thousands other stars in
our MUSE survey of 26 Galactic globular clusters. Assuming that at least a few
exotic stars have exotic spectra, that means spectra that contain emission
lines, we can use this large spectroscopic data set of over a million stellar
spectra as a blind survey to detect stellar exotica in globular clusters. To
detect emission lines in each spectrum, we model the expected shape of an
emission line as a Gaussian curve. This template is used for matched filtering
on the differences between each observed 1D spectrum and its fitted spectral
model. The spectra with the most significant detections of H$\alpha$ emission
are checked visually and cross-matched with published catalogues. We find 156
stars with H$\alpha$ emission, including several known cataclysmic variables
(CV) and two new CVs, pulsating variable stars, eclipsing binary stars, the
optical counterpart of a known black hole, several probable sub-subgiants and
red stragglers, and 21 background emission-line galaxies. We find possible
optical counterparts to 39 X-ray sources, as we detect H$\alpha$ emission in
several spectra of stars that are close to known positions of Chandra X-ray
sources. This spectral catalogue can be used to supplement existing or future
X-ray or radio observations with spectra of potential optical counterparts to
classify the sources.
