Testing thermal reprocessing in active galactic nuclei accretion discs
By E. Cackett, K. Horne, H. Winkler. 2007
218 citations recorded by the source corpus.
The thermal reprocessing hypothesis in active galactic nuclei (AGN), where extreme ultraviolet/X-ray photons are reprocessed by the accretion disc into optical/UV photons, predicts wavelength-dependent time-delays between the optical continuum at different wavelengths. Recent photometric monitoring by Sergeev et al. has shown that the time-delay is observed in 14 AGN, and generally seen to increase with increasing wavelength, as predicted in the reprocessing scenario. We fit the observed time-delays and optical spectral energy distribution using a disc reprocessing model. The model delivers estimates for the nuclear reddening, the product of black hole mass and accretion rate, and the distance to each object. However, the distances at face value give H0 = 44 ± 5k m s −1 Mpc −1 ‐ a factor of 1.6 smaller than generally accepted. We discuss the implications of this on the reprocessing model.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/e2481574a52815050587949e58ef348592ba19ac
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In Astronomy and Astrophysics
Citations in the corpus
- REVERBERATION MEASUREMENTS OF THE INNER RADIUS OF THE DUST TORUS IN 17 SEYFERT GALAXIES (2014, methodology): “Cackett et al. (2007) estimated the intrinsic color excess of 14 AGNs by the flux variation gradient (FVG) method (Winkler et al. 1992) and the Balmer decrement method.”
- Now You See It, Now You Don't: The Disappearing Central Engine of the Quasar J1011+5442 (2015, unknown): “This because the optical continuum may result from illumination from the inner disk, as suggested by the results of reverberation studies (e.g., Krolik et al. 1991; Cackett et al. 2007).”
- THE MAN BEHIND THE CURTAIN: X-RAYS DRIVE THE UV THROUGH NIR VARIABILITY IN THE 2013 ACTIVE GALACTIC NUCLEUS OUTBURST IN NGC 2617 (2013, background): “Lags between shorter- and longer-wavelength continuum variations have been detected in several sources (e.g., Sergeev et al. 2005; Cackett et al. 2007) at marginal significance, and always in the sense that the short-wavelength variations lead those at longer wavelengths.”
- X-ray reverberation around accreting black holes (2014, background): “In fact, the variations in the optical continuum on day-to-week timescales in AGN, which show short (sub-day) red-lags (e.g. Cackett et al. 2007), can likely only be explained by thermal reverberation of the disc in response to the rapidly-varying central EUV/X-ray source.”
- SPACE TELESCOPE AND OPTICAL REVERBERATION MAPPING PROJECT. II. SWIFT AND HST REVERBERATION MAPPING OF THE ACCRETION DISK OF NGC 5548 (2015, unknown): “This is shown in Equations 1 and 2 of Cackett et al. (2007) and Equation 4.56 of Netzer (2013).”
- A systematic search for changing-look quasars in SDSS (2015, background): “In the disk reprocessing model of Cackett et al. (2007), the disk temperature T0 at a fiducial radius R0 is regulated by both local viscous heating and irradiation: T 40 = T 4 infl + T 4 irr = 3GMBHṀ 8πσR30 + LX(1−A)h 4πσR30 , (2) where LX is the lamp post luminosity at a height h above the black…”
- Active galactic nuclei: what’s in a name? (2017, result): “Indeed, the derived lag amplitude-wavelength dependence is consistent with that expected from reprocessing of X-rays in a standard disk (e.g. Cackett et al. 2007; Edelson et al. 2015).”
- THE DISCOVERY OF THE FIRST “CHANGING LOOK” QUASAR: NEW INSIGHTS INTO THE PHYSICS AND PHENOMENOLOGY OF ACTIVE GALACTIC NUCLEI (2014, background): “Nonetheless, the observed variability of the optical continuum is probably driven by reprocessing of UV or X-ray light, as discussed by Krolik et al. (1991) and Cackett et al. (2007) and can be as rapid as the variability in those higher-frequency bands.”