A Negative Long Lag from the Optical to the UV Continuum in Fairall 9

Abstract

We report the detection of a long-timescale negative lag, where the blue bands lag the red bands, in the nearby Seyfert 1 galaxy Fairall 9. Active Galactic Nuclei (AGN) light curves show variability over a wide range of timescales. By measuring time lags between different wavelengths, the otherwise inaccessible structure and kinematics of the accretion disk can be studied. One common approach, reverberation mapping, quantifies the continuum and line lags moving outwards through the disk at the light-travel time, revealing the size and temperature profile of the disk. Inspired by numerical simulations, we expect longer lags to exist in AGN light curves that travel inward on longer timescales, tracing the accretion process itself. By analyzing AGN light curves in both temporal and frequency space, we report the detection of long-timescale lags ($\sim -70$ days) in Fairall 9 which propagate in the opposite direction to the reverberation lag. The short continuum lag ($<10$ days) is also detected and is consistent with reverberation lags reported in the literature. When fitting the longer lag as a function of frequency with a model motivated by the thin disk model, we find that the disk scale height likely increases outward in the disk. This detection raises the exciting prospect of mapping accretion disk structures across a wide range of AGN parameters.

24 pages, 14 figures, submitted to ApJ

References in corpus (24)

• X-ray reverberation around accreting black holes
• Is Quasar Optical Variability a Damped Random Walk?
• Space Telescope and Optical Reverberation Mapping Project. II. Swift and HST Reverberation Mapping of the Accretion Disk of NGC 5548
• Reverberation mapping of Active Galactic Nuclei: from X-ray corona to dusty torus
• Space Telescope and Optical Reverberation Mapping Project. I. Ultraviolet Observations of the Seyfert 1 Galaxy NGC 5548 with the Cosmic Origins Spectrograph on Hubble Space Telescope
• Swift monitoring of NGC 5548: X-ray reprocessing and short term UV/optical variability
• Discovery of multiple Lorentzian components in the X-ray timing properties of the Narrow Line Seyfert 1 Ark 564
• Are the Variability Properties of the Kepler AGN Light Curves Consistent with a Damped Random Walk?
• Magnetohydrodynamic Simulations of Active Galactic Nucleus Disks and Jets
• Correlated X-ray/Optical Variability in the Quasar MR2251-178
• Intensive disc-reverberation mapping of Fairall 9: 1st year of Swift & LCO monitoring
• Space Telescope and Optical Reverberation Mapping Project VI: reverberating Disk Models for NGC 5548
• UV/optical disk thermal reverberation in AGN: an in-depth study with an analytic prescription for the time-lag spectra
• Optical Variability of Quasars with 20-Year Photometric Light Curves
• On the multi-wavelength variability of Mrk 110: Two components acting at different timescales
• X-ray Variability of the Seyfert 1 Markarian 335: Power Spectrum and Time Lags
• Opacity Driven Convection and Variability in Accretion Disks around Supermassive Black Holes
• Evidence for variability timescale dependent UV/X-ray delay in Seyfert 1 AGN NGC 7469
• Frequency-resolved lags in UV/optical continuum reverberation mapping
• Using AGN lightcurves to map accretion disc temperature fluctuations
• Correlated X-ray/UV/optical variability and the nature of accretion disc in the bare Seyfert 1 galaxy Fairall~9
• Optical continuum photometric reverberation mapping of the Seyfert-1 galaxy Mrk509
• Modelling Continuum Reverberation in AGN: A Spectral-Timing Analysis of the UV Variability Through X-ray Reverberation in Fairall 9
• Variability Selected Active Galactic Nuclei from ASAS-SN Survey: Constraining the Low Luminosity AGN Population

Cited by in corpus (5)

• AGN STORM 2. VII. A Frequency-resolved Map of the Accretion Disk in Mrk 817: Simultaneous X-ray Reverberation and UVOIR Disk Reprocessing Time Lags
• Connecting the X-ray/UV variability of Fairall 9 with NICER: A Possible Warm Corona
• Joint Modeling of Quasar Variability and Accretion Disk Reprocessing using Latent Stochastic Differential Equations
• The UV/optical Continuum Reverberation Mapping of Eight Active Galactic Nuclei with Swift: Further Evidence for the Outer Component
• Untangling the Complex Nature of AGN Variability with Fairall 9