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TAPIR Seminar

Friday, May 24, 2019
2:00pm to 3:00pm
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Cahill 370
Assembly bias, galactic conformity, and the galaxy-halo connection
Angela Berti, Graduate Student, Department of Physics, University of California, San Diego,

The halo model of galaxy evolution assumes all properties of a galaxy are determined statistically by the mass of its host halo. While this assumption yields predictions that largely agree with observations, the full picture of the galaxy-halo connection is incomplete without assembly bias. Halo assembly bias refers to the dependence of present-day halo clustering on factors besides mass, such as a halo's age and assembly history, and is predicted by cosmological simulations. Probes of galaxy assembly bias include galactic conformity and the differential clustering of star-forming and quiescent central galaxies at fixed stellar mass. In this talk I will explain why two-halo galactic conformity is likely not a real effect, and demonstrate that efforts to refine galaxy evolution models should instead focus on correlations between halo accretion rate and galaxy properties like star formation rate. I will also show why observers should utilize mock galaxy surveys based on empirical models to correct for systematic errors and get the most out of existing galaxy surveys.

For more information, please contact JoAnn Boyd by phone at 4280 or by email at