  Stellar streams, long thin streams of stars, have been used as sensitive
probes of dark matter substructure for over two decades. Gravitational
interactions between dark matter substructures and streams lead to the
formation of low density "gaps" in streams, with any given stream typically
containing no more than a few such gaps. Prior models for the statistics of
such gaps have relied on several simplifying assumptions for the properties of
the subhalo population in the cold dark matter scenario. With the expected
forthcoming increase in the number of streams, and gaps, observed, in this work
we develop a more detailed model for the statistics of subhalos interacting
with streams, and test some of the assumptions made in prior works. Instead of
using simple fits to N-body estimates of subhalo population statistics at z = 0
as in previous work, we make use of realizations of time-dependent subhalo
populations generated from a fully physical model, incorporating structure
formation, and subhalo orbital evolution, including tidal heating and stripping
physics, which has been carefully calibrated to match results of cosmological
N-body simulations. We find that this model predicts up to 60% more gaps on
average in Pal-5-like streams than prior works.
