Black Holes Big and Small: Probing the Wimpiest Accretion Flows and their Jets

Dr. Richard M. Plotkin

Department of Astronomy,

University of Michigan

Tuesday, February 4, 2013

3:30 p.m., Room 104, Physics Building

Refreshments

3:15 p.m., Room 104

ABSTRACT: Black holes broach an amazingly diverse range of subfields in physics, at every conceivable size-scale. At the most fundamental level, black holes challenge our current understanding of physics, potentially bridging the gap between general relativity and quantum gravity. In astrophysical contexts, black holes may play a prominent role in the evolutionary history of entire galaxies. A supermassive black hole (millions to billions times the mass of the Sun, with an event horizon more compact than our Solar System) probably lurks at the center of every large galaxy. If matter falls onto these black holes, the infalling mass will form an accretion disk, which in turn releases radiation across nearly the entire electromagnetic spectrum. Accreting black holes also sometimes launch jets of relativistic plasma that carry large amounts of kinetic energy away from the black hole. In this talk, I will describe how we exploit radiative signatures from accretion flows and their jets to learn about black holes. To better understand supermassive black holes, I actually turn to their lower-mass cousins: stellar mass black holes found in our own Galaxy. Stellar mass black holes offer a unique advantage in that they evolve on human timescales of only months to years, providing an opportunity to directly probe how disk/jet systems respond to changes in accretion rate. I use multiwavelength observations to track stellar mass black holes down to the lowest detectable accretion rates, and I will describe how we can use that knowledge to better understand the impact that the energy released from supermassive black holes may have on cosmological size-scales.