Title: Galactic accretion and galaxy structure in the cold dark matter model

Speaker:Andrew Cooper (NAOC)

Time:Thursday, 3:00pm,27th June

Location: Lecture Theatre, 3rd floor

One of the major outstanding puzzles of galactic astronomy is why galaxies have the great variety of different shapes and sizes we observe. In this talk, I'll first review theories that connect the structure of galaxies (quantified by surface brightness profiles) to their evolution. Although a host of upcoming ultra-deep photometric surveys (notably LSST) are about to reveal the complex outer structure of galaxies in unprecedented detail, surprisingly few large simulations have tested even these well-known ideas as an integrated part of CDM galaxy formation. The work I'll present focuses on one of the easier parts of this problem -- the structure of massive elliptical galaxies. I'll show new predictions for the structure of ellipticals, based on a novel way of combining semi-analytic models and N-body simulations, and explain why these turn out to be remarkably consistent with observational data -- the fundamental reason is the importance of galactic accretion and merging. I'll discuss the insights our simulations give into familiar but little-understood observational phenomena, including the galaxy mass-size relation, cD galaxies and intracluster light. I'll also mention how these concepts (and our simulations) are relevant to the stellar haloes of much less massive galaxies like the Milky Way.