Space Telescope and Optical Reverberation Mapping Project. VI. reverberating disk models for NGC 5548

D. Starkey, Keith Horne, M. M. Fausnaugh, B. M. Peterson, M. C. Bentz, C. S. Kochanek, K. D. Denney, R. Edelson, M. R. Goad, G. De Rosa, M. D. Anderson, P. Arévalo, A. J. Barth, C. Bazhaw, G. A. Borman, T. A. Boroson, M. C. Bottorff, W. N. Brandt, A. A. Breeveld, E. M. CackettM. T. Carini, K. V. Croxall, D. M. Crenshaw, E. Dalla Bonta, Adriana De Lorenzo-Caceres Rodriguez, M. Dietrich, N. V. Efimova, J. Ely, P. A. Evans, A. V. Filippenko, K. Flatland, N. Gehrels, S. Geier, J. M. Gelbord, L. Gonzalez, V. Gorjian, C. J. Grier, D. Grupe, P. B. Hall, S. Hicks, D. Horenstein, T. Hutchison, M. Im, J. J. Jensen, M. D. Joner, J. Jones, J. Kaastra, S. Kaspi, B. C. Kelly, J. A. Kennea, S. C. Kim, M. Kim, S. A. Klimanov, K. T. Korista, G. A. Kriss, J. C. Lee, D. C. Leonard, P. Lira, F. MacInnis, E. R. Manne-Nicholas, S. Mathur, I. M. McHardy, C. Montouri, R. Musso, S. V. Nazarov, R. P. Norris, J. A. Nousek, D. N. Okhmat, A. Pancoast, J. R. Parks, L. Pei, R. W. Pogge, J. -U. Pott, S. E. Rafter, H. W. Rix, D. A. Saylor, J. S. Schimoia, K. Schnulle, S. G. Sergeev, M. H. Siegel, M. Spencer, H. -I. Sung, K. G. Teems, C. S. Turner, P. Uttley, M. Vestergaard, C. Villforth, Y. Weiss, J. -H. Woo, H. Yan, S. Young, W. Zheng, Y. Zu

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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) 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.
Original languageEnglish
Article number65
Number of pages15
JournalAstrophysical Journal
Issue number1
Early online date18 Jan 2017
Publication statusPublished - 20 Jan 2017


  • Accretion
  • Accretion disks
  • Galaxies: active
  • Galaxies: individual (NGC 5548)
  • Galaxies: nuclei
  • Galaxies: Seyfert


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