Space Telescope and Optical Reverberation Mapping Project. VIII. Time Variability of Emission and Absorption in NGC 5548 Based on Modeling the Ultraviolet Spectrum
AffiliationUniv Arizona, Steward Observ
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PublisherIOP PUBLISHING LTD
CitationG. A. Kriss et al 2019 ApJ 881 153
RightsCopyright © 2019. The American Astronomical Society.
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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 Lyα 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 Lyα 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 ~105 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 ~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.
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SponsorsNASA; Space Telescope Science Institute; National Science Foundation (NSF); NSF [AST-1412315]; Padua University [AST-1412693]; NSF CAREER grant [DOR1699945/16, DOR1715817/17, DOR1885254/18, BIRD164402/16]; NASA through Chandra award [AST-1253702]; HHMI [AR7-18013X, NAS8-03060, HST-AR-13240.009]; NSF Fellowship [AST-1302093]; ADAP [NNX13AC26G, NNX13AC63G, NNX13AE99G]; STScI [ATP 17-0141]; Huffaker scholarship [HST-AR-13914, HST-AR-15018]; Polish National Science Center grant Polonez [2016/21/P/ST9/04025]; NSERC [NNH13CH61C]; UK Science and Technology Facilities Council [ST/J001651/1]; National Research Foundation of Korea (NRF); National Research Foundation of Korea (NRF) - Korean government (MSIT) [2017R1A3A3001362]; NWO, the Netherlands Organization for Scientific Research [AST-0618209]; UC Center for Galaxy Evolution; Fondecyt [AST-1009571, AST-1210311]; NSF graduate fellowship ; UCSB Dean's Fellowship; NOVA; Nederlandse Onderzoekschool voor Astronomie; CNPq; National Council for Scientific and Technological Development (Brazil); Packard Foundation in the form of a Packard Research Fellowship; TABASGO Foundation; Christopher R. Redlich Fund; Miller Institute for Basic Research in Science (UC Berkeley); Danish Council for Independent Research [DFF 4002-00275]; National Research Foundation of Korea (NRF) - Korean government; National Aeronautics and Space Administration [2010-0027910]