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, Elena Dalla Bontà, A. De Lorenzo-Cáceres, 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. Schnülle, 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, And S. Young, W. Zheng, Y. Zu

Research output: Contribution to journalArticlepeer-review

63 Scopus citations


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 A oto 9157 A o) 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 ) × 10 3 K at 1 light day from the black hole, and a temperatureradius slope (T ∞r-a) of a = 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 (US)
Article number65
JournalAstrophysical Journal
Issue number1
StatePublished - Jan 20 2017
Externally publishedYes


  • accretion, accretion disks
  • galaxies: Seyfert
  • galaxies: active
  • galaxies: individual (NGC 5548)
  • galaxies: nuclei

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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