Return of dark-matter self-interactions?

Abstract:
Models of self-interacting dark matter (SIDM)—models in which dark
matter can have up to strong-scale interactions with like particles in a
hidden sector—had their first heyday in the early 2000’s, to explain the
dearth of small galaxies near our Milky Way.  In this talk, I will
explore why these models fell out of favor for a decade, and why they’ve
come roaring back since ~2010.  I will show how small galaxies near the
Milky Way can probe a new type of cosmic SIDM phenomenology, and how
other observations on small scales can map out the allowed regions of
SIDM parameter space.