Seminar

Mapping Accretion and Ejection in Black Holes

April 19, 2018

Erin Kara

Accreting supermassive black holes can produce more electromagnetic and kinetic luminosities than the combined stellar luminosity of an entire galaxy. Most of the power output from an Active Galactic Nucleus is released close to the black hole, and therefore studying the inner accretion flow--at the intersection of inflow and outflow--is essential for understanding how black holes grow and how they affect their surrounding environments. In this talk, I will present a new way of probing these environments, through X-ray reverberation mapping. Similar to optical reverberation, where light travel time delays of days or weeks map out kiloparsec scales in the Broad Line Region, X-ray reverberation reveals time delays of tens of seconds, which map out microparsec scales close to the black hole event horizon. In addition to persistently accreting black holes, Tidal Disruption Events, where a star gets ripped apart by the strong tidal forces of a supermassive black hole, allow us to probe the innermost region around black holes that would otherwise appear dormant. The stellar debris can accrete at rates exceeding the Eddington limit, and so, these transient events also provide a tool for probing extreme accretion and the fast, massive outflows that ensue. New spectral and timing studies of black holes are changing how we understand accretion and ejection in time-variable and transient systems, and thanks to upcoming instruments, like LSST and ESA’s Athena Observatory, the future is bright.

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