  Within the hierarchical framework for galaxy formation, merging and tidal
interactions are expected to shape large galaxies to this day. While major
mergers are quite rare at present, minor mergers and satellite disruptions -
which result in stellar streams - should be common, and are indeed seen in both
the Milky Way and the Andromeda Galaxy. As a pilot study, we have carried out
ultra-deep, wide-field imaging of some spiral galaxies in the Local Volume,
which has revealed external views of such stellar tidal streams at
unprecedented detail, with data taken at small robotic telescopes
(0.1-0.5-meter) that provide exquisite surface brightness sensitivity. The goal
of this project is to undertake the first systematic and comprehensive imaging
survey of stellar tidal streams, from a sample of ~50 nearby Milky-Way-like
spiral galaxies within 15 Mpc, that features a surface brightness sensitivity
of ~ 30 mag/arcsec^2 The survey will result in estimates of the incidence,
size/geometry and stellar luminosity/mass distribution of such streams. This
will not only put our Milky Way and M31 in context but, for the first time,
also provide an extensive statistical basis for comparison with
state-of-the-art, self-consistent cosmological simulations of this phenomenon.

Astrophysics