Colloquia Postings

Satellite Galaxies as Tracers of Dark Matter Halos

Speaker: Dr. Tereasa Brainerd (Boston University)
Time: November 22, 2019 - 3:00 PM
Location: Atrium 101


Small, faint satellite galaxies, orbiting within the gravitational potentials of large, bright “host” galaxies have the potential to place powerful constraints on the relationship between dark and luminous matter on scales < 500 kpc.  It has long been hoped, and a number of simulations have strongly suggested, that the satellites of isolated host galaxies are “fair tracers” of the dark matter distribution that surrounds the hosts.  Over the past decade or so, observational studies of the satellites of isolated host galaxies have led to a number of interesting conclusions.  In terms of their spatial distributions, satellite galaxies are, on average, distributed anisotropically with respect to their hosts’ major axes.  In addition, some observational studies have concluded that the radial density profiles of satellite galaxies (i.e., the number of satellites per unit area on the sky) are consistent with the expectations of the Cold Dark Matter (CDM) model, but others have suggested that the profiles are inconsistent with CDM.  Here I’ll discuss a number of recent observational and theoretical studies that are aimed at answering two key questions: [1] In the context of CDM, should we actually expect satellite galaxies to be fair tracers of the dark matter distribution around isolated host galaxies? and [2] Is the CDM model able to reproduce all of the observations of satellite galaxies that we currently have? 


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