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 \mathringA to 9157 \mathringA ) 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^\circ +/- 10^\circ , temperature {T}1=(44+/- 6)× {10}3 K at 1 light day from the black hole, and a temperature-radius slope (T\propto {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/{L}{Edd}=0.1.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2017
- DOI:
- 10.3847/1538-4357/835/1/65
- arXiv:
- arXiv:1611.06051
- Bibcode:
- 2017ApJ...835...65S
- Keywords:
-
- accretion;
- accretion disks;
- galaxies: active;
- galaxies: individual: NGC 5548;
- galaxies: nuclei;
- galaxies: Seyfert;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- V2: Oops wrong title! V1: Accepted for publication in ApJ, 20 Pages, 11 Figures