A Caltech Library Service

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

Pei, L. and Adams, Scott M. (2017) Space Telescope and Optical Reverberation Mapping Project. V. Optical Spectroscopic Campaign and Emission-line Analysis for NGC 5548. Astrophysical Journal, 837 (2). Art. No. 131. ISSN 1538-4357.

[img] PDF - Published Version
See Usage Policy.

[img] PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


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) days and 0.79^(+0.35)_(-0.34) 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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Adams, Scott M.0000-0001-5855-5939
Additional Information:© 2017 American Astronomical Society. Received 2016 October 20; revised 2017 January 12; accepted 2017 February 3; published 2017 March 10. 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 NSF grant AST-0618209. SRON is financially supported by NWO, the Netherlands Organization for Scientific Research. B.C.K. is partially supported by the UC Center for Galaxy Evolution. C.S.K. acknowledges the support of NSF grant AST-1009756. D.C.L. acknowledges support from NSF grants AST-1009571 and AST-1210311. P.L. acknowledges support from Fondecyt grant no. 1161184. A.P. acknowledges support from an NSF graduate fellowship and a UCSB Deans Fellowship. J.S.S. acknowledges CNPq, National Council for Scientific and Technological Development (Brazil) for partial support and The Ohio State University for warm hospitality. N.T. acknowledges support from CONICYT PAI/82140055. T.T. has been supported by NSF grant AST-1412315. T.T. and B.C.K. acknowledge support from the Packard Foundation in the form of a Packard Research Fellowship to T.T. Also, T.T. thanks the American Academy in Rome and the Observatory of Monteporzio Catone for kind hospitality. The Dark Cosmology Centre is funded by the Danish National Research Foundation. M.V. gratefully acknowledges support from the Danish Council for Independent Research via grant no. DFF 4002-00275. J.-H.W. acknowledges support by the National Research Foundation of Korea (NRF) grant funded by the Korean government (no. 2010-0027910). This work is based partly on observations obtained with the Apache Point Observatory 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium. Research at Lick Observatory is partially supported by a generous gift from Google. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We thank the anonymous referee for the thorough review and comments that helped improve the clarity of this manuscript.
Funding AgencyGrant Number
Christopher R. Redlich FundUNSPECIFIED
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Science and Technology Facilities Council (STFC)ST/M001296/1
Department of Energy (DOE)DE-FG02-97ER25308
National Research Foundation of Korea2008-0060544
Ministry of Science, ICT and Future Planning (Korea)UNSPECIFIED
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)UNSPECIFIED
UC Center for Galaxy EvolutionUNSPECIFIED
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1161184
NSF Graduate Research FellowshipUNSPECIFIED
University of California Santa BarbaraUNSPECIFIED
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)UNSPECIFIED
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)PAI/82140055
David and Lucile Packard FoundationUNSPECIFIED
Danish National Research FoundationUNSPECIFIED
Danish Council for Independent ResearchDFF 4002-00275
National Research Foundation of Korea2010-0027910
Subject Keywords:galaxies: active – galaxies: individual (NGC 5548) – galaxies: nuclei – galaxies: Seyfert Supporting material: machine-readable table
Issue or Number:2
Record Number:CaltechAUTHORS:20170310-142719574
Persistent URL:
Official Citation:L. Pei et al 2017 ApJ 837 131
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:75035
Deposited By: Tony Diaz
Deposited On:10 Mar 2017 23:04
Last Modified:03 Oct 2019 16:45

Repository Staff Only: item control page