@inproceedings{8435f1d998bd44c5b4aab52c55e50100,
title = "Probing quasar shutdown timescales with Hanny's Voorwerp",
abstract = "Galaxy formation is significantly modulated by energy output from supermassive black holes at the centers of galaxies which grow in highly efficient luminous quasar phases. The timescale on which black holes transition into and out of such phases is, however, unknown. We present the first measurement of the shutdown timescale for an individual quasar using Suzaku and XMM-Newton X-ray observations of the nearby galaxy IC 2497, which hosted a luminous quasar no more than ∼230,000 years ago that is still seen as a light echo in 'Hanny's Voorwerp', but whose presentday radiative output is lower by at least 2 and more likely by over 4 orders of magnitude. This extremely rapid shutdown provides new insights into the physics of accretion in supermassive black holes, and may signal a transition of the accretion disk to a radiatively inefficient state. These results were first presented by [1].",
keywords = "(galaxies:) quasars: general, (galaxies:) quasars: individual (IC 2497)",
author = "Evans, {Daniel A.} and Kevin Schawinski and Shanil Virani and Urry, {C. Megan} and Keel, {William C.} and Priyamvada Natarajan and Lintott, {Chris J.} and Anna Manning and Paolo Coppi and Sugata Kaviraj and Bamford, {Steven P.} and J{\'o}zsa, {Gyula I.G.} and Michael Garrett and {Van Arkel}, Hanny and Pamela Gay and Fortson, {Lucy F}",
year = "2012",
doi = "10.1063/1.3696176",
language = "English (US)",
isbn = "9780735410107",
series = "AIP Conference Proceedings",
pages = "193--200",
booktitle = "SUZAKU 2011 - Exploring the X-Ray Universe",
note = "Suzaku 2011: Exploring the X-Ray Universe: Suzaku and Beyond ; Conference date: 20-07-2011 Through 22-07-2011",
}