Dust Reverberation Mapping in Distant Quasars from Optical and Mid-Infrared Imaging Surveys

Abstract

The size of the dust torus in Active Galactic Nuclei (AGN) and their high-luminosity counterparts, quasars, can be inferred from the time delay between UV/optical accretion disk continuum variability and the response in the mid-infrared (MIR) torus emission. This dust reverberation mapping (RM) technique has been successfully applied to $\sim 70$ $z\lesssim 0.3$ AGN and quasars. Here we present first results of our dust RM program for distant quasars covered in the SDSS Stripe 82 region combining $\sim 20$-yr ground-based optical light curves with 10-yr MIR light curves from the WISE satellite. We measure a high-fidelity lag between W1-band (3.4 $\mu$m) and $g$ band for 587 quasars over $0.3\lesssim z\lesssim 2$ ($⟨z⟩\sim 0.8$) and two orders of magnitude in quasar luminosity. They tightly follow (intrinsic scatter $\sim 0.17$ dex in lag) the IR lag-luminosity relation observed for $z<0.3$ AGN, revealing a remarkable size-luminosity relation for the dust torus over more than four decades in AGN luminosity, with little dependence on additional quasar properties such as Eddington ratio and variability amplitude. This study motivates further investigations in the utility of dust RM for cosmology, and strongly endorses a compelling science case for the combined 10-yr Vera C. Rubin Observatory Legacy Survey of Space and Time (optical) and 5-yr Nancy Grace Roman Space Telescope 2$\mu$m light curves in a deep survey for low-redshift AGN dust RM with much lower luminosities and shorter, measurable IR lags. The compiled optical and MIR light curves for 7,384 quasars in our parent sample are made public with this work.

Accepted for publication in ApJ

References in corpus (20)

• The Zwicky Transient Facility: System Overview, Performance, and First Results
• A Catalog of Quasar Properties from SDSS DR7
• Some Aspects of Measurement Error in Linear Regression of Astronomical Data
• An Observational Determination of the Bolometric Quasar Luminosity Function
• Initial Performance of the NEOWISE Reactivation Mission
• Modeling the Time Variability of SDSS Stripe 82 Quasars as a Damped Random Walk
• Is Quasar Optical Variability a Damped Random Walk?
• Resolving the complex structure of the dust torus in the active nucleus of the Circinus galaxy
• Radiative Transfer Modeling of Three-Dimensional Clumpy AGN Tori and its Application to NGC 1068
• Reverberation Measurements of the Inner Radius of the Dust Torus in 17 Seyfert Galaxies
• The innermost region of AGN tori: implications from the HST/NICMOS Type 1 point sources and near-IR reverberation
• The Sloan Digital Sky Survey Reverberation Mapping Project: Technical Overview
• Mid-infrared variability of changing-look AGN
• The characteristic blue spectra of accretion disks in quasars as uncovered in the infrared
• Detection of Time Lags Between Quasar Continuum Emission Bands based on Pan-STARRS Light-curves
• Variation of Inner Radius of Dust Torus in NGC4151
• A New Method for Measuring Extragalactic Distances
• Spitzer Space Telescope Measurements of Dust Reverberation Lags in the Seyfert 1 Galaxy NGC 6418
• Modeling the Infrared Reverberation Response of the Circumnuclear Dusty Torus in AGN: The Effects of Cloud Orientation and Anisotropic Illumination
• Calibration of AGN Reverberation Distance Measurements

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