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dc.contributor.authorEdelson, R.
dc.contributor.authorGelbord, J.
dc.contributor.authorCackett, E. M.
dc.contributor.authorConnolly, S.
dc.contributor.authorDone, C.
dc.contributor.authorFausnaugh, M.
dc.contributor.authorGardner, E.
dc.contributor.authorGehrels, N.
dc.contributor.authorGoad, M.
dc.contributor.authorHorne, K.
dc.contributor.authorMcHardy, I.
dc.contributor.authorPeterson, B. M.
dc.contributor.authorVaughan, S.
dc.contributor.authorVestergaard, Marianne
dc.contributor.authorBreeveld, A. A.
dc.contributor.authorBarth, A. J.
dc.contributor.authorBentz, Misty C.
dc.contributor.authorBottorff, M.
dc.contributor.authorBrandt, W. N.
dc.contributor.authorCrawford, S. M.
dc.contributor.authorBonta, E. Dalla
dc.contributor.authorEmmanoulopoulos, D.
dc.contributor.authorEvans, P.
dc.contributor.authorJaimes, R. Figuera
dc.contributor.authorFilippenko, A. V.
dc.contributor.authorFerland, G. J.
dc.contributor.authorGrupe, D.
dc.contributor.authorJoner, M.
dc.contributor.authorKennea, J. A.
dc.contributor.authorKorista, K. T.
dc.contributor.authorKrimm, H. A.
dc.contributor.authorKriss, G.
dc.contributor.authorLeonard, D. C.
dc.contributor.authorMathur, S.
dc.contributor.authorNetzer, H.
dc.contributor.authorNousek, J.
dc.contributor.authorPage, K.
dc.contributor.authorRomero-Colmenero, E.
dc.contributor.authorSiegel, M.
dc.contributor.authorStarkey, D. A.
dc.contributor.authorTreu, T.
dc.contributor.authorVogler, H. A.
dc.contributor.authorWinkler, H.
dc.contributor.authorZheng, W.
dc.date.accessioned2017-06-23T19:16:21Z
dc.date.available2017-06-23T19:16:21Z
dc.date.issued2017-05-03
dc.identifier.citationSwift Monitoring of NGC 4151: Evidence for a Second X-Ray/UV Reprocessing 2017, 840 (1):41 The Astrophysical Journalen
dc.identifier.issn1538-4357
dc.identifier.doi10.3847/1538-4357/aa6890
dc.identifier.urihttp://hdl.handle.net/10150/624341
dc.description.abstractSwift monitoring of NGC 4151 with an similar to 6 hr sampling over a total of 69 days in early 2016 is used to construct light curves covering five bands in the X-rays (0.3-50 keV) and six in the ultraviolet (UV)/optical (1900-5500 angstrom). The three hardest X-ray bands (> 2.5 keV) are all strongly correlated with no measurable interband lag, while the two softer bands show lower variability and weaker correlations. The UV/optical bands are significantly correlated with the X-rays, lagging similar to 3-4 days behind the hard X-rays. The variability within the UV/optical bands is also strongly correlated, with the UV appearing to lead the optical by similar to 0.5-1 days. This combination of greater than or similar to 3 day lags between the X-rays and UV and less than or similar to 1 day lags within the UV/optical appears to rule out the "lamp-post" reprocessing model in which a hot, X-ray emitting corona directly illuminates the accretion disk, which then reprocesses the energy in the UV/optical. Instead, these results appear consistent with the Gardner & Done picture in which two separate reprocessings occur: first, emission from the corona illuminates an extreme-UV-emitting toroidal component that shields the disk from the corona; this then heats the extreme-UV component, which illuminates the disk and drives its variability.
dc.description.sponsorshipNASA [NNX13AC26G, NNX13AC63G, NNX13AE99G, NNH13CH61C]; NSF [AST-1412693, AST-1253702, AST-1211916, AST-1009571, AST-1210311, AST-1412315]; STFC [ST/M001296/1]; National Research Foundation (NRF) of South Africa; UK Space Agency; TABASGO Foundation; Christopher R. Redlich Fund; Packard Foundation; Danish Council for Independent Research [DFF 4002-00275]en
dc.language.isoenen
dc.publisherIOP PUBLISHING LTDen
dc.relation.urlhttp://stacks.iop.org/0004-637X/840/i=1/a=41?key=crossref.4593b5fd47ed97abb254e75023ef72f1en
dc.rights© 2017. The American Astronomical Society. All rights reserved.en
dc.subjectgalaxies: activeen
dc.subjectgalaxies: individual (NGC 4151)en
dc.subjectgalaxies: nucleien
dc.subjectgalaxies: Seyferten
dc.titleSwift Monitoring of NGC 4151: Evidence for a Second X-Ray/UV Reprocessingen
dc.typeArticleen
dc.contributor.departmentUniv Arizona, Steward Observen
dc.identifier.journalThe Astrophysical Journalen
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en
dc.eprint.versionFinal published versionen
refterms.dateFOA2018-06-17T22:31:33Z
html.description.abstractSwift monitoring of NGC 4151 with an similar to 6 hr sampling over a total of 69 days in early 2016 is used to construct light curves covering five bands in the X-rays (0.3-50 keV) and six in the ultraviolet (UV)/optical (1900-5500 angstrom). The three hardest X-ray bands (> 2.5 keV) are all strongly correlated with no measurable interband lag, while the two softer bands show lower variability and weaker correlations. The UV/optical bands are significantly correlated with the X-rays, lagging similar to 3-4 days behind the hard X-rays. The variability within the UV/optical bands is also strongly correlated, with the UV appearing to lead the optical by similar to 0.5-1 days. This combination of greater than or similar to 3 day lags between the X-rays and UV and less than or similar to 1 day lags within the UV/optical appears to rule out the "lamp-post" reprocessing model in which a hot, X-ray emitting corona directly illuminates the accretion disk, which then reprocesses the energy in the UV/optical. Instead, these results appear consistent with the Gardner & Done picture in which two separate reprocessings occur: first, emission from the corona illuminates an extreme-UV-emitting toroidal component that shields the disk from the corona; this then heats the extreme-UV component, which illuminates the disk and drives its variability.


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