Speaker: Mark Alford (Washington Univ St. Louis)

Title: Neutron star mergers as materials science

Abstract: Neutron star mergers are laboratories for hot and dense nuclear matter. In a merger, the stellar material experiences violent changes in temperature and density that happen in milliseconds. This means that mergers probe dynamical properties that may help us uncover the phase structure of ultra-dense matter. I will describe the most promising dynamical property, bulk viscosity. I will explain how bulk viscosity arises and how we estimate its importance in neutron star mergers.

Short Bio: Prof Mark Alford obtained his PhD from Harvard U in 1990 and was then postdoctoral researcher at UCSB, Cornell U, the Institute for Adv​anced Studies, Princeton, and MIT. He joined the faculty of University of St. Louis as an assistant professor in 2003 and was the chair of the physics department from 2012 to 2022. Professor Alford's research seeks to understand the properties of matter at ultra-high density, such as might be reached in the core of a neutron star, where atoms and even nuclei are crushed into exotic phases of unimaginable density. One of the main aims of Alford's work is to find signatures of the presence of color superconducting quark matter in neutron stars. His work therefore incorporates aspects of particle physics, nuclear physics, condensed matter physics, and astrophysics. In the past he has worked on numerical lattice QCD calculations, developing improved actions that greatly increase the efficiency of these computations, and also looking for ways to apply numerical methods at high density.