Mini mergers with major consequences in a cold dark matter universe

Connor Bottrell (University of Western Australia)

Abstract:

The gravitational forces measured beyond the Solar System tell us that 85% of the matter in the Universe is invisible. But despite its abundance, dark matter has so-far avoided direct detection by laboratory experiments on Earth. As a result, particle physics theory has flourished to develop dark matter candidates that span a wide range of masses and phenomenologies. In this talk, I will discuss some consequences of dark matter physics on galaxies including the predicted abundances of low-mass dark matter halos. In particular, I will show that “mini” collisions with low-mass halos have an inconspicuously important role in driving diversity amongst large star-forming galaxies in cosmological simulations. These collisions are ubiquitous in the Cold Dark Matter cosmogony, but suppressed by warmer, lighter dark matter particles.