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Space Telescope and Optical Reverberation Mapping Project. VIII. Time Variability of Emission and Absorption in NGC 5548 Based on Modeling the Ultraviolet Spectrum

dc.contributor.authorSomers, G.
dc.descriptionOnly Vanderbilt University affiliated authors are listed on VUIR. For a full list of authors, access the version of record at
dc.description.abstractWe model the ultraviolet spectra of the Seyfert 1 galaxy NGC 5548 obtained with the Hubble Space Telescope during the 6 month reverberation mapping campaign in 2014. Our model of the emission from NGC 5548 corrects for overlying absorption and deblends the individual emission lines. Using the modeled spectra, we measure the response to continuum variations for the deblended and absorption-corrected individual broad emission lines, the velocity-dependent profiles of Ly alpha and C IV, and the narrow and broad intrinsic absorption features. We find that the time lags for the corrected emission lines are comparable to those for the original data. The velocity-binned lag profiles of Ly alpha and C IV have a double-peaked structure indicative of a truncated Keplerian disk. The narrow absorption lines show a delayed response to continuum variations corresponding to recombination in gas with a density of similar to 10(5) cm(-3). The high-ionization narrow absorption lines decorrelate from continuum variations during the same period as the broad emission lines. Analyzing the response of these absorption lines during this period shows that the ionizing flux is diminished in strength relative to the far-ultraviolet continuum. The broad absorption lines associated with the X-ray obscurer decrease in strength during this same time interval. The appearance of X-ray obscuration in similar to 2012 corresponds with an increase in the luminosity of NGC 5548 following an extended low state. We suggest that the obscurer is a disk wind triggered by the brightening of NGC 5548 following the decrease in size of the broad-line region during the preceding low-luminosity state.en_US
dc.description.sponsorshipWe thank R. Plesha for formatting and posting the high-level data products in MAST. 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. M.M.F., G.D.R., B.M.P., C.J.G., and R.W.P. are grateful for the support of the National Science Foundation (NSF) through grant AST-1008882 to The Ohio State University. A.J.B. and L.P. have been supported by NSF grant AST-1412693. E.M.C., E.D.B., L.M., and A.P. acknowledge support from Padua University through grants DOR1699945/16, DOR1715817/17, DOR1885254/18, and BIRD164402/16. M.C.B. gratefully acknowledges support through NSF CAREER grant AST-1253702 to Georgia State University. S. B. was supported by NASA through Chandra award No. AR7-18013X issued by the Chandra X-ray Observatory Center, operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060. S. B. was also partially supported by grant HST-AR-13240.009. M.C.B. 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. R.E. gratefully acknowledges support from NASA under awards NNX13AC26G, NNX13AC63G, and NNX13AE99G and ADAP award 80NSSC17K0126. G.J. F. and M.D. thank the NSF (1816537), NASA (ATP 17-0141), and STScI (HST-AR-13914, HST-AR-15018) for their support and the Huffaker scholarship for funding related travel. B.D.M. acknowledges support from Polish National Science Center grant Polonez 2016/21/P/ST9/04025. 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/J001651/1. M.I. acknowledges support from National Research Foundation of Korea (NRF) grant No. 2017R1A3A3001362. M.K. was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (No. 2017R1C1B2002879). 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 grants AST-1814440 and AST-1515876. D.C.L. acknowledges support from NSF grants AST-1009571 and AST-1210311. P.L. acknowledges support from Fondecyt grant No. 1120328. A.P. acknowledges support from an NSF graduate fellowship and a UCSB Dean's Fellowship. C. S. acknowledges support from NOVA, the Nederlandse Onderzoekschool voor Astronomie. J.S.S. acknowledges CNPq, the National Council for Scientific and Technological Development (Brazil), for partial support and The Ohio State University for warm hospitality. 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. Support for A.V.F.'s group at UC Berkeley is provided by the TABASGO Foundation, the Christopher R. Redlich Fund, and the Miller Institute for Basic Research in Science (UC Berkeley). M.V. and J.J.J. gratefully acknowledge 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 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.en_US
dc.publisherAstrophysical Journalen_US
dc.rightsOriginal content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
dc.subjectgalaxies: individual (NGC 5548)en_US
dc.subjectgalaxies: nucleien_US
dc.subjectgalaxies: Seyferten_US
dc.subjectgalaxies: activeen_US
dc.titleSpace Telescope and Optical Reverberation Mapping Project. VIII. Time Variability of Emission and Absorption in NGC 5548 Based on Modeling the Ultraviolet Spectrumen_US

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