Probing quasar shutdown timescales with Hanny's Voorwerp

Daniel A. Evans, Kevin Schawinski, Shanil Virani, C. Megan Urry, William C. Keel, Priyamvada Natarajan, Chris J. Lintott, Anna Manning, Paolo Coppi, Sugata Kaviraj, Steven P. Bamford, Gyula I.G. Józsa, Michael Garrett, Hanny Van Arkel, Pamela Gay, Lucy F Fortson

Research output: Chapter in Book/Report/Conference proceedingConference contribution


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].

Original languageEnglish (US)
Title of host publicationSUZAKU 2011 - Exploring the X-Ray Universe
Subtitle of host publicationSuzaku and Beyond
Number of pages8
StatePublished - 2012
EventSuzaku 2011: Exploring the X-Ray Universe: Suzaku and Beyond - Palo Alto, CA, United States
Duration: Jul 20 2011Jul 22 2011

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


OtherSuzaku 2011: Exploring the X-Ray Universe: Suzaku and Beyond
CountryUnited States
CityPalo Alto, CA


  • (galaxies:) quasars: general
  • (galaxies:) quasars: individual (IC 2497)


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