Date/Time
Date(s) - 23/03/2016
3:30 pm - 4:30 pm

Title: Why Stars Matter for Galaxies

Speaker: Dr. Phil Hopkins

Institute: California Institute of Technology

Location: ABB 102

Description:

Galaxies are commonly believed to form “top-down” as gravity condenses matter from the cosmic web, first into a disk of gas, and then within that disk into stars. But this has led to decades of fundamental, unsolved problems. We now realize that stars, once formed, are not simply passive “tracers” of the galaxy and gravity. They act: they radiate energy which is absorbed by surrounding gas and dust, they blow winds, they explode as supernovae, and they form black holes that can themselves grow and shine. The energetics of these processes are sufficient to re-shape the galaxies themselves as well as the inter-galactic medium. I’ll describe how modern simulations incorporate this enormous dynamic range of physics into an understanding of how star formation, galaxy formation, and black hole growth form self-regulating “feedback loops.” These can explain long-standing puzzles and a wealth of observations, produce remarkably uniform scaling laws across ~10 decades or more in spatial and mass scale, and shed light on the nature of dark matter.