The Hough Stream Spotter: A New Method for Detecting Linear Structure in
  Resolved Stars and Application to the Stellar Halo of M31
  Stellar streams from globular clusters (GCs) offer constraints on the nature
of dark matter and have been used to explore the dark matter halo structure and
substructure of our Galaxy. Detection of GC streams in other galaxies would
broaden this endeavor to a cosmological context, yet no such streams have been
detected to date. To enable such exploration, we develop the Hough Stream
Spotter (HSS), and apply it to the Pan-Andromeda Archaeological Survey (PAndAS)
photometric data of resolved stars in M31's stellar halo. We first demonstrate
that our code can re-discover known dwarf streams in M31. We then use the HSS
to blindly identify 27 linear GC stream-like structures in the PAndAS data. For
each HSS GC stream candidate, we investigate the morphologies of the streams
and the colors and magnitudes of all stars in the candidate streams. We find
that the five most significant detections show a stronger signal along the red
giant branch in color-magnitude diagrams (CMDs) than spurious non-stream
detections. Lastly, we demonstrate that the HSS will easily detect globular
cluster streams in future Nancy Grace Roman Space Telescope data of nearby
galaxies. This has the potential to open up a new discovery space for GC stream
studies, GC stream gap searches, and for GC stream-based constraints on the
nature of dark matter.
