Space Telescope and Optical Reverberation Mapping Project. VI. : reverberating disk models for NGC 5548
Abstract
We conduct a multiwavelength continuum variability study of the Seyfert 1 galaxy NGC 5548 to investigate the temperature structure of its accretion disk. The 19 overlapping continuum light curves (1158 Å to 9157 Å) combine simultaneous Hubble Space Telescope, Swift, and ground-based observations over a 180 day period from 2014 January to July. Light-curve variability is interpreted as the reverberation response of the accretion disk to irradiation by a central time-varying point source. Our model yields the disk inclination i = 36° ± 10°, temperature T1 =(44 ± 6) x 103 K at 1 light day from the black hole, and a temperature–radius slope (T α r-α) of α = 0.99 ± 0.03. We also infer the driving light curve and find that it correlates poorly with both the hard and soft X-ray light curves, suggesting that the X-rays alone may not drive the ultraviolet and optical variability over the observing period. We also decompose the light curves into bright, faint, and mean accretion-disk spectra. These spectra lie below that expected for a standard blackbody accretion disk accreting at L/LEdd=0.1.
Citation
Starkey , D , Horne , K , Fausnaugh , M M , Peterson , B M , Bentz , M C , Kochanek , C S , Denney , K D , Edelson , R , Goad , M R , Rosa , G D , Anderson , M D , Arévalo , P , Barth , A J , Bazhaw , C , Borman , G A , Boroson , T A , Bottorff , M C , Brandt , W N , Breeveld , A A , Cackett , E M , Carini , M T , Croxall , K V , Crenshaw , D M , Bonta , E D , De Lorenzo-Caceres Rodriguez , A , Dietrich , M , Efimova , N V , Ely , J , Evans , P A , Filippenko , A V , Flatland , K , Gehrels , N , Geier , S , Gelbord , J M , Gonzalez , L , Gorjian , V , Grier , C J , Grupe , D , Hall , P B , Hicks , S , Horenstein , D , Hutchison , T , Im , M , Jensen , J J , Joner , M D , Jones , J , Kaastra , J , Kaspi , S , Kelly , B C , Kennea , J A , Kim , S C , Kim , M , Klimanov , S A , Korista , K T , Kriss , G A , Lee , J C , Leonard , D C , Lira , P , MacInnis , F , Manne-Nicholas , E R , Mathur , S , McHardy , I M , Montouri , C , Musso , R , Nazarov , S V , Norris , R P , Nousek , J A , Okhmat , D N , Pancoast , A , Parks , J R , Pei , L , Pogge , R W , Pott , J -U , Rafter , S E , Rix , H W , Saylor , D A , Schimoia , J S , Schnulle , K , Sergeev , S G , Siegel , M H , Spencer , M , Sung , H -I , Teems , K G , Turner , C S , Uttley , P , Vestergaard , M , Villforth , C , Weiss , Y , Woo , J -H , Yan , H , Young , S , Zheng , W & Zu , Y 2017 , ' Space Telescope and Optical Reverberation Mapping Project. VI. reverberating disk models for NGC 5548 ' , Astrophysical Journal , vol. 835 , no. 1 , 65 . https://doi.org/10.3847/1538-4357/835/1/65
Publication
Astrophysical Journal
Status
Peer reviewed
ISSN
0004-637XType
Journal article
Description
D.A.S. and K.D.H. acknowledge support from the UK Science and Technology Facilities Council through grant ST/K502339/1 and ST/J001651/1.Collections
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