Colloquium Event

Seeing to the Event Horizons of Supermassive Black Holes

Abstract

Supermassive black holes in the centers of galaxies power some of the brightest objects we see in the Universe; active galactic nuclei (AGN). Much remains unknown, however, about exactly how energy is released from the material falling in through the accretion disk, and from the black hole itself, to power these extreme systems, forming a powerful X-ray emitting corona and launching jets at almost the speed of light.

The X-rays emitted from the corona illuminate the material falling into the black hole and by measuring its reflection, we obtain a unique insight into the processes occurring just outside the event horizon. Most recently, measuring echoes of X-ray flares emitted by the corona, and comparing these measurements to the predictions of general relativistic ray tracing simulations, we have been able to obtain the most detailed map of the structure of the inner accretion disk and corona.

The reverberation of X-ray flares is letting us see the corona evolve in real time and witness the effects of strong gravity and general relativity as the X-rays are bent around the black hole. This gives us important insight into the small-scale processes close to the event horizon that allow black holes to power these extreme objects and play their important feedback role in the formation of structure in the Universe.

Speaker Name

Dan Wilkins

Speaker Institution

Kavli Institute, Stanford University

Speaker Information

Dan Wilkins is a research scientist in the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University. Dan received his doctorate in Astronomy from the University of Cambridge in 2009. After a short research fellowship in Halifax, Nova Scotia, he was awarded NASA’s prestigious Einstein Fellowship which brought him to Stanford in 2016.

His research focuses on supermassive black holes at the centers of galaxies, how matter plunging into them powers some of the most extreme objects we see in the Universe. He has pioneered studies of the X-rays that reflect and reverberate off of the material falling into the black hole to map out the extreme environment just outside the event horizon. Alongside research into supermassive black holes, Dan is working towards the development of some the next generation space-based X-ray observatories. He is a member of the instrument team for the next-generation Athena X-ray observatory, planned for launch in the next decade, and part of the science working groups for smaller, specialized mission concepts to complement the capabilities of the flagship observatories.

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