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Space Telescope and Optical Reverberation Mapping Project. V. Optical Spectroscopic Campaign and Emission-Line Analysis for NGC 5548

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posted on 2017-04-03, 11:11 authored by L. Pei, M. M. Fauanaugh, A. J. Barth, B. M. Peterson, M. C. Bentz, G. De Rosa, K. D. Denney, M. R. Goad, C. S. Kochanek, K. T. Korista, G. A. Kriss, R. P. Norris, J. A. Nousek, D. N. Okhmat, I. Papadakis, J. R. Parks, J.-U. Pott, S. E. Rafter, H.-W. Rix, D. A. Saylor, K. I. Clubb, Miao Li, K. Schnülle, S. G. Sergeev, M. Siegel, A. Skielboe, M. Spencer, D. Starkey, H.-I. Sung, K. G. Teems, C. S. Turner, P. Uttley, Cassandra Lochhaas, E. Dalla Bontà, C. Villforth, Y. Weiss, J.-H. Woo, H. Yan22, S. Young58, A. V. Filippenko, J. E. Greene, C. J. Grier, M. Vestergaard, Zhiyuan Ma, W. Zheng, Scott M. Adams, Thomas G. Beatty, A. Bigley, Jacob E. Brown, Jonathan S. Brown, G. Canalizo, J. M. Comerford, Carl T. Coker, E. M. Corsini, E. R. Manne-Nicholas, S. Croft, K. V. Croxall, A. J. Deason, Michael Eracleous, O. D. Fox, E. L. Gates, C. B. Henderson, E. Holmbeck, T. W.-S. Holoien, J. J. Jensen, J. C. Mauerhan, C. A. Johnson, P. L. Kelly, S. Kim, A. King, M. W. Lau, M. A. Malkan, R McGurk, L. Morelli, Ana Mosquera, Dale Mudd, K. Flatland, F. Muller Sanchez, M. L. Nguyen, P. Ochner, B. Ou-Yang, A. Pancoast, Matthew T. Penny, A. Pizzella, Radosław Poleski, Jessie Runnoe, B. Scott, N. Gehrels, Jaderson S. Schimoia, B. J. Shappee, I. Shivvers, Gregory V. Simonian, A. Siviero, Garrett Somers, Daniel J. Stevens, M. A. Strauss, Jamie Tayar, N. Tejos, S. Geier, T. Treu, J. Van Saders, L. Vican, S. Villanueva Jr., H. Yuk, N. L. Zakamska, W. Zhu, M. D. Anderson, P. Arévalo, C. Bazhaw, J. M. Gelbord, S. Bisogni, G. A. Borman, M. C. Bottorff, W. N. Brandt, A. A. Breeveld, E. M. Cackett, M. T. Carini, D. M. Crenshaw, A. De Lorenzo-Cáceres, M. Dietrich, D. Grupe, R. Edelson, N. V. Efimova, J. Ely, P. A. Evans, G. J. Ferland, A. Gupta, P. B. Hall, S. Hicks, D. Horenstein, Keith Horne, R. W. Pogge, T. Hutchison, M. Im, M. D. Joner, J. Jones, J. Kaastra, S. Kaspi, B. C. Kelly, J. A. Kennea, M. Kim, S. C. Kim, V. N. Bennert, S. A. Klimanov, J. C. Lee, D. C. Leonard, P. Lira, F. MacInnis, S. Mathur, I. M. McHardy, C. Montouri, R. Musso, S. V. Nazarov, M. Brotherton, H. Netzer, Y. Zu
We present the results of an optical spectroscopic monitoring program targeting NGC 5548 as part of a larger multiwavelength reverberation mapping campaign. The campaign spanned 6 months and achieved an almost daily cadence with observations from five ground-based telescopes. The Hβ and He ii λ4686 broad emission-line light curves lag that of the 5100 Å optical continuum by ${4.17}_{-0.36}^{+0.36}\,\mathrm{days}$ and ${0.79}_{-0.34}^{+0.35}\,\mathrm{days}$, respectively. The Hβ lag relative to the 1158 Å ultraviolet continuum light curve measured by the Hubble Space Telescope is ~50% longer than that measured against the optical continuum, and the lag difference is consistent with the observed lag between the optical and ultraviolet continua. This suggests that the characteristic radius of the broad-line region is ~50% larger than the value inferred from optical data alone. We also measured velocity-resolved emission-line lags for Hβ and found a complex velocity-lag structure with shorter lags in the line wings, indicative of a broad-line region dominated by Keplerian motion. The responses of both the Hβ and He ii emission lines to the driving continuum changed significantly halfway through the campaign, a phenomenon also observed for C iv, Lyα, He ii(+O iii]), and Si iv(+O iv]) during the same monitoring period. Finally, given the optical luminosity of NGC 5548 during our campaign, the measured Hβ lag is a factor of five shorter than the expected value implied by the R BLR–L AGN relation based on the past behavior of NGC 5548.

Funding

We thank the staffs at the various observatories used to obtain the data in this paper. Support for HST program no. GO-13330 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. L.P. and A.J.B. have been supported by National Science Foundation (NSF) grant AST-1412693. M.M.F., G.D.R., B.M.P., C.J.G., and R.W.P. are grateful for the support of NSF grant AST-1008882 to The Ohio State University. M.C. Bentz gratefully acknowledges support through NSF CAREER grant AST-1253702 to Georgia State University. A.V.F.'s group at UC Berkeley is grateful for financial assistance from NSF grant AST-1211916, the TABASGO Foundation, and the Christopher R Redlich Fund. C.S.K. is supported by NSF grant AST-1515876. V.N.B. gratefully acknowledges assistance from NSF Research at Undergraduate Institutions (RUI) grant AST-1312296. M.C. Bottorff acknowledges HHMI for support through an undergraduate science education grant to Southwestern University. K.D.D. is supported by an NSF Fellowship awarded under grant AST-1302093. M.E. thanks the members of the Center for Relativistic Astrophysics at Georgia Tech and the Department of Astronomy at the University of Washington, where he was based during the observing campaign, for their warm hospitality. R.E. gratefully acknowledges support from NASA under awards NNX13AC26G, NNX13AC63G, and NNX13AE99G. J.M.G. gratefully acknowledges support from NASA under award NNH13CH61C. P.B.H. is supported by NSERC. K.H. acknowledges support from the UK Science and Technology Facilities Council through grant ST/M001296/1. T.W.-S.H. is supported by the DOE Computational Science Graduate Fellowship, grant no. DE-FG02-97ER25308. M.I. acknowledges support from the Creative Initiative program, no. 2008-0060544, of the National Research Foundation of Korea (NRFK) funded by the Korean government (MSIP). M.D.J. acknowledges

History

Citation

Astrophysical Journal, 2017, 837(2)

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy

Version

  • VoR (Version of Record)

Published in

Astrophysical Journal

Publisher

American Astronomical Society, IOP Publishing

issn

0004-637X

eissn

1538-4357

Acceptance date

2017-02-03

Copyright date

2017

Available date

2017-04-03

Publisher version

http://iopscience.iop.org/article/10.3847/1538-4357/aa5eb1

Language

en

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