Characterization of Low Surface Brightness structures in annotated deep
  images
  The characterization of Low Surface Brightness (LSB) stellar structures
around galaxies such as tidal debris of on-going or past collisions is
essential to constrain models of galactic evolution. Our goal is to obtain
quantitative measurements of LSB structures identified in deep images of
samples consisting of hundreds of galaxies. We developed an online annotation
tool that enables contributors to delineate the shapes of diffuse extended
stellar structures, as well as artefacts or foreground structures. All
parameters are automatically stored in a database which may be queried to
retrieve quantitative measurements. We annotated LSB structures around 352
nearby massive galaxies with deep images obtained with the CFHT as part of two
large programs: MATLAS and UNIONS/CFIS. Each LSB structure was delineated and
labeled according to its likely nature: stellar shells, streams associated to a
disrupted satellite, tails formed in major mergers, ghost reflections or
cirrus. From our database containing 8441 annotations, the area, size, median
surface brightness and distance to the host of 228 structures were computed.
The results confirm the fact that tidal structures defined as streams are
thinner than tails, as expected by numerical simulations. In addition, tidal
tails appear to exhibit a higher surface brightness than streams (by about 1
mag), which may be related to different survival times for the two types of
collisional debris. We did not detect any tidal feature fainter than 27.5
mag.arcsec$^{-2}$, while the nominal surface brightness limits of our surveys
range between 28.3 and 29 mag.arcsec$^{-2}$, a difference that needs to be
taken into account when estimating the sensitivity of future surveys to
identify LSB structures. Our annotation database of observed LSB structures may
be used for quantitative analysis and as a training set for machine learning
algorithms (abbreviated).
