Colloquium

Reverberation mapping of the inner accretion flow around black holes

Active Galactic Nuclei can produce as much or more electromagnetic and kinetic luminosities than the combined stellar luminosity of an entire galaxy. Though the masses of the central black holes are typically 500-1000 times less their host galaxies, AGN appear to play a vital role in regulating the growth of the most massive galaxies. The energy output from AGN comes from only two sources: the gravitational potential energy of the infalling material and the rotational energy of the black hole. In both cases, most of the energy is released very close to the black hole, and therefore, probing the relativistic region of the inner accretion flow is essential to understanding how AGN work and effect their environments. In this talk, I will present a new way of probing these extreme, relativistic environments, through X-ray reverberation mapping, which allows us to map the gas falling on to the black hole and measure the effects of strongly curved spacetime close to the event horizon. I will give an overview of the recent discoveries in X-ray reverberation mapping, and discuss how this technique is being used to put new constraints on the X-ray emitting region and the accretion disc geometry. Lastly, I will present the recent discovery of reverberation in a tidal disruption event, which shows the formation of a super-Eddington accretion flow around a usually quiescent black hole.

Followed by wine and cheese in Pupin 1402

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