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Galaxy Zoo: 'Hanny's Voorwerp', a quasar light echo?

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dc.contributor.authorLintott, Chris J.
dc.contributor.authorSchawinski, Kevin
dc.contributor.authorKeel, William
dc.contributor.authorvan Arkel, Hanny
dc.contributor.authorBennert, Nicola
dc.contributor.authorEdmondson, Edward
dc.contributor.authorThomas, Daniel
dc.contributor.authorSmith, Daniel J. B.
dc.contributor.authorHerbert, Peter D.
dc.contributor.authorJarvis, Matt J.
dc.contributor.authorVirani, Shanil
dc.contributor.authorAndreescu, Dan
dc.contributor.authorBamford, Steven P.
dc.contributor.authorLand, Kate
dc.contributor.authorMurray, Phil
dc.contributor.authorNichol, Robert C.
dc.contributor.authorRaddick, M. Jordan
dc.contributor.authorSlosar, Anze
dc.contributor.authorSzalay, Alex
dc.contributor.authorVandenberg, Jan
dc.contributor.otherUniversity of Oxford
dc.contributor.otherYale University
dc.contributor.otherUniversity of Alabama Tuscaloosa
dc.contributor.otherUniversity of California System
dc.contributor.otherUniversity of California Riverside
dc.contributor.otherUniversity of California Santa Barbara
dc.contributor.otherUniversity of Portsmouth
dc.contributor.otherLiverpool John Moores University
dc.contributor.otherUniversity of Hertfordshire
dc.contributor.otherJohns Hopkins University
dc.contributor.otherUnited States Department of Energy (DOE)
dc.contributor.otherLawrence Berkeley National Laboratory
dc.contributor.otherUniversity of California Berkeley
dc.date.accessioned2018-09-21T21:44:56Z
dc.date.available2018-09-21T21:44:56Z
dc.date.issued2009
dc.description.abstractWe report the discovery of an unusual object near the spiral galaxy IC 2497, discovered by visual inspection of the Sloan Digital Sky Survey (SDSS) as part of the Galaxy Zoo project. The object, known as Hanny's Voorwerp, is bright in the SDSS g band due to unusually strong [O III]4959, 5007 emission lines. We present the results of the first targeted observations of the object in the optical, ultraviolet and X-ray, which show that the object contains highly ionized Gas. Although the line ratios are similar to extended emission-line regions near luminous active galactic nucleus (AGN), the source of this ionization is not apparent. The emission-fine properties, and lack of X-ray emission from IC 2497, suggest either a highly obscured AGN with a novel geometry arranged to allow photoionization of the object but not the galaxy's own circumnuclear gas, or, as we argue, the first detection of a quasar light echo. In this case, either the luminosity of the central source has decreased dramatically or else the obscuration in the system has increased within 10(5) yr. This object may thus represent the first direct probe of quasar history on these time-scales.en_US
dc.format.mimetypeapplication/pdf
dc.identifier.citationLintott, C. et al. (2009): Galaxy Zoo: ‘Hanny's Voorwerp’, a quasar light echo? Monthly Notices of the Royal Astronomical Society, 399(1). DOI: https://doi.org/10.1111/j.1365- 2966.2009.15299.x
dc.identifier.doi10.1111/j.1365-2966.2009.15299.x
dc.identifier.orcidhttps://orcid.org/0000-0001-7821-7195
dc.identifier.orcidhttps://orcid.org/0000-0001-5464-0888
dc.identifier.orcidhttps://orcid.org/0000-0002-6325-5671
dc.identifier.orcidhttps://orcid.org/0000-0002-4108-3282
dc.identifier.orcidhttps://orcid.org/0000-0003-0503-5782
dc.identifier.orcidhttps://orcid.org/0000-0001-9708-253X
dc.identifier.urihttp://ir.ua.edu/handle/123456789/3944
dc.languageEnglish
dc.language.isoen_US
dc.publisherOxford University Press
dc.rights.licenseAttribution 4.0 International (CC BY 4.0)
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subjectgalaxies: active
dc.subjectgalaxies: individual: IC 2497
dc.subjectgalaxies: peculiar
dc.subjectquasars: general
dc.subjectACTIVE GALACTIC NUCLEI
dc.subjectDIGITAL-SKY-SURVEY
dc.subjectEMISSION-LINE REGIONS
dc.subjectHUBBLE-SPACE-TELESCOPE
dc.subjectSTAR-FORMING GALAXIES
dc.subjectHOST GALAXIES
dc.subjectINFRARED GALAXIES
dc.subjectSTELLAR OBJECTS
dc.subjectRADIO JET
dc.subjectIMAGES
dc.subjectAstronomy & Astrophysics
dc.titleGalaxy Zoo: 'Hanny's Voorwerp', a quasar light echo?en_US
dc.typetext
dc.typeArticle

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