Space Telescope and Optical Reverberation Mapping Project. VI. : reverberating disk models for NGC 5548
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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.
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 . DOI: 10.3847/1538-4357/835/1/65
© 2017, American Astronomical Society. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at iopscience.iop.org / http://dx.doi.org/10.3847/1538-4357/835/1/65
DescriptionD.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.
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