Swift Monitoring of NGC 4151: Evidence for a Second X-Ray/UV Reprocessing

R. Edelson; J. Gelbord; E. Cackett; S. Connolly; C. Done; M. Fausnaugh; E. Gardner; N. Gehrels; M. Goad; K. Horne; I. McHardy; B. M. Peterson; S. Vaughan; M. Vestergaard; A. Breeveld; A. J. Barth; M. Bentz; M. Bottorff; W. N. Brandt; S. M. Crawford; Elena Dalla Bontà; D. Emmanoulopoulos; P. Evans; R. Figuera Jaimes; A. V. Filippenko; G. Ferland; D. Grupe; M. Joner; J. Kennea; K. T. Korista; H. A. Krimm; G. Kriss; D. C. Leonard; S. Mathur; H. Netzer; J. Nousek; K. Page; E. Romero-Colmenero; M. Siegel; D. A. Starkey; T. Treu; H. A. Vogler; H. Winkler; W. Zheng

doi:10.3847/1538-4357/aa6890

Swift Monitoring of NGC 4151: Evidence for a Second X-Ray/UV Reprocessing

R. Edelson, J. Gelbord, E. Cackett, S. Connolly, C. Done, M. Fausnaugh, E. Gardner, N. Gehrels, M. Goad, K. Horne, I. McHardy, B. M. Peterson, S. Vaughan, M. Vestergaard, A. Breeveld, A. J. Barth, M. Bentz, M. Bottorff, W. N. Brandt, S. M. CrawfordElena Dalla Bontà, D. Emmanoulopoulos, P. Evans, R. Figuera Jaimes, A. V. Filippenko, G. Ferland, D. Grupe, M. Joner, J. Kennea, K. T. Korista, H. A. Krimm, G. Kriss, D. C. Leonard, S. Mathur, H. Netzer, J. Nousek, K. Page, E. Romero-Colmenero, M. Siegel, D. A. Starkey, T. Treu, H. A. Vogler, H. Winkler, W. Zheng

School of Physics and Astronomy

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Abstract

Swift monitoring of NGC 4151 with an ∼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 Å). 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 ∼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 ∼0.5-1 days. This combination of ≳3 day lags between the X-rays and UV and ≲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.

Original language	English
Article number	41
Journal	Astrophysical Journal
Volume	840
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/aa6890
State	Published - 1 May 2017

Keywords

galaxies: Seyfert
galaxies: active
galaxies: individual (NGC 4151)
galaxies: nuclei

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10.3847/1538-4357/aa6890

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Edelson, R., Gelbord, J., Cackett, E., Connolly, S., Done, C., Fausnaugh, M., Gardner, E., Gehrels, N., Goad, M., Horne, K., McHardy, I., Peterson, B. M., Vaughan, S., Vestergaard, M., Breeveld, A., Barth, A. J., Bentz, M., Bottorff, M., Brandt, W. N., ... Zheng, W. (2017). Swift Monitoring of NGC 4151: Evidence for a Second X-Ray/UV Reprocessing. Astrophysical Journal, 840(1), Article 41. https://doi.org/10.3847/1538-4357/aa6890

@article{705264f48dd64ea0bf603451e0e369bd,

title = "Swift Monitoring of NGC 4151: Evidence for a Second X-Ray/UV Reprocessing",

abstract = "Swift monitoring of NGC 4151 with an ∼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 {\AA}). 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 ∼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 ∼0.5-1 days. This combination of ≳3 day lags between the X-rays and UV and ≲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.",

keywords = "galaxies: Seyfert, galaxies: active, galaxies: individual (NGC 4151), galaxies: nuclei",

author = "R. Edelson and J. Gelbord and E. Cackett and S. Connolly and C. Done and M. Fausnaugh and E. Gardner and N. Gehrels and M. Goad and K. Horne and I. McHardy and Peterson, {B. M.} and S. Vaughan and M. Vestergaard and A. Breeveld and Barth, {A. J.} and M. Bentz and M. Bottorff and Brandt, {W. N.} and Crawford, {S. M.} and {Dalla Bont{\`a}}, Elena and D. Emmanoulopoulos and P. Evans and Jaimes, {R. Figuera} and Filippenko, {A. V.} and G. Ferland and D. Grupe and M. Joner and J. Kennea and Korista, {K. T.} and Krimm, {H. A.} and G. Kriss and Leonard, {D. C.} and S. Mathur and H. Netzer and J. Nousek and K. Page and E. Romero-Colmenero and M. Siegel and Starkey, {D. A.} and T. Treu and Vogler, {H. A.} and H. Winkler and W. Zheng",

year = "2017",

month = may,

day = "1",

doi = "10.3847/1538-4357/aa6890",

language = "אנגלית",

volume = "840",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "IOP Publishing Ltd.",

number = "1",

}

Edelson, R, Gelbord, J, Cackett, E, Connolly, S, Done, C, Fausnaugh, M, Gardner, E, Gehrels, N, Goad, M, Horne, K, McHardy, I, Peterson, BM, Vaughan, S, Vestergaard, M, Breeveld, A, Barth, AJ, Bentz, M, Bottorff, M, Brandt, WN, Crawford, SM, Dalla Bontà, E, Emmanoulopoulos, D, Evans, P, Jaimes, RF, Filippenko, AV, Ferland, G, Grupe, D, Joner, M, Kennea, J, Korista, KT, Krimm, HA, Kriss, G, Leonard, DC, Mathur, S, Netzer, H, Nousek, J, Page, K, Romero-Colmenero, E, Siegel, M, Starkey, DA, Treu, T, Vogler, HA, Winkler, H & Zheng, W 2017, 'Swift Monitoring of NGC 4151: Evidence for a Second X-Ray/UV Reprocessing', Astrophysical Journal, vol. 840, no. 1, 41. https://doi.org/10.3847/1538-4357/aa6890

TY - JOUR

T1 - Swift Monitoring of NGC 4151

T2 - Evidence for a Second X-Ray/UV Reprocessing

AU - Edelson, R.

AU - Gelbord, J.

AU - Cackett, E.

AU - Connolly, S.

AU - Done, C.

AU - Fausnaugh, M.

AU - Gardner, E.

AU - Gehrels, N.

AU - Goad, M.

AU - Horne, K.

AU - McHardy, I.

AU - Peterson, B. M.

AU - Vaughan, S.

AU - Vestergaard, M.

AU - Breeveld, A.

AU - Barth, A. J.

AU - Bentz, M.

AU - Bottorff, M.

AU - Brandt, W. N.

AU - Crawford, S. M.

AU - Dalla Bontà, Elena

AU - Emmanoulopoulos, D.

AU - Evans, P.

AU - Jaimes, R. Figuera

AU - Filippenko, A. V.

AU - Ferland, G.

AU - Grupe, D.

AU - Joner, M.

AU - Kennea, J.

AU - Korista, K. T.

AU - Krimm, H. A.

AU - Kriss, G.

AU - Leonard, D. C.

AU - Mathur, S.

AU - Netzer, H.

AU - Nousek, J.

AU - Page, K.

AU - Romero-Colmenero, E.

AU - Siegel, M.

AU - Starkey, D. A.

AU - Treu, T.

AU - Vogler, H. A.

AU - Winkler, H.

AU - Zheng, W.

PY - 2017/5/1

Y1 - 2017/5/1

N2 - Swift monitoring of NGC 4151 with an ∼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 Å). 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 ∼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 ∼0.5-1 days. This combination of ≳3 day lags between the X-rays and UV and ≲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.

AB - Swift monitoring of NGC 4151 with an ∼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 Å). 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 ∼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 ∼0.5-1 days. This combination of ≳3 day lags between the X-rays and UV and ≲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.

KW - galaxies: Seyfert

KW - galaxies: active

KW - galaxies: individual (NGC 4151)

KW - galaxies: nuclei

UR - http://www.scopus.com/inward/record.url?scp=85019146385&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/aa6890

DO - 10.3847/1538-4357/aa6890

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AN - SCOPUS:85019146385

SN - 0004-637X

VL - 840

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 41

ER -

Swift Monitoring of NGC 4151: Evidence for a Second X-Ray/UV Reprocessing

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Keywords

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