Modeling the Time Variability of SDSS Stripe 82 Quasars as a Damped Random Walk

Abstract

We model the time variability of ~9,000 spectroscopically confirmed quasars in SDSS Stripe 82 as a damped random walk. Using 2.7 million photometric measurements collected over 10 years, we confirm the results of Kelly et al. (2009) and Kozłowski et al. (2010) that this model can explain quasar light curves at an impressive fidelity level (0.01-0.02 mag). The damped random walk model provides a simple, fast [O(N) for N data points], and powerful statistical description of quasar light curves by a characteristic time scale (tau) and an asymptotic rms variability on long time scales (SF_inf). We searched for correlations between these two variability parameters and physical parameters such as luminosity and black hole mass, and rest-frame wavelength. We find that tau increases with increasing wavelength with a power law index of 0.17, remains nearly constant with redshift and luminosity, and increases with increasing black hole mass with power law index of 0.21+/-0.07. The amplitude of variability is anti-correlated with the Eddington ratio, which suggests a scenario where optical fluctuations are tied to variations in the accretion rate. The radio-loudest quasars have systematically larger variability amplitudes by about 30%, when corrected for the other observed trends, while the distribution of their characteristic time scale is indistinguishable from that of the full sample. We do not detect any statistically robust differences in the characteristic time scale and variability amplitude between the full sample and the small subsample of quasars detected by ROSAT. Our results provide a simple quantitative framework for generating mock quasar light curves, such as currently used in LSST image simulations. (abridged)

39 pages, accepted to ApJ

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• The Timescale-Dependent Color Variability of Quasars Viewed with GALEX
• Universality in the Random Walk Structure Function of Luminous Quasi-Stellar Objects
• Ionization driven intrinsic absorption line variability of BAL quasars in the Stripe 82 region
• Time Series Analysis of Active Galactic Nuclei: The case of Arp 102B, 3C 390.3, NGC 5548 and NGC 4051
• LSST Cadence Strategy Evaluations for AGN Time-series Data in Wide-Fast-Deep Field
• The Time-Domain Spectroscopic Survey: Understanding the Optically Variable Sky with SEQUELS in SDSS-III
• Constraining quasar structure using high-frequency microlensing variations and continuum reverberation
• The Curious Case of PHL 293B: A Long-Lived Transient in a Metal-Poor Blue Compact Dwarf Galaxy
• Spectral Energy Distributions of Candidate Periodically-Variable Quasars: Testing the Binary Black Hole Hypothesis
• Correlation between Optical and UV Variability of Quasars
• A 6.4yr optical quasi-periodic oscillations in SDSS J075217.84+193542.2: a new candidate for central binary black hole system
• A Gravitationally Lensed Quasar Discovered in OGLE
• Kepler light curve analysis of the blazar W2R 1926+42
• Do the Kepler AGN Light Curves Need Re-processing?
• The Mass-Richness Relation of MaxBCG Clusters from Quasar Lensing Magnification using Variability
• Properties of long-term optical variability of active galactic nuclei with double-peaked broad low-ionization emission lines
• Constraints on accretion disk size in the massive type 1 quasar PG 2308+098 from optical continuum reverberation lags
• An intrinsic link between long-term UV/optical variations and X-ray loudness in quasars
• Flares in the changing look AGN Mrk 590. I: The UV response to X-ray outbursts suggests a more complex reprocessing geometry than a standard disk
• Imprints of the quasar structure in time-delay light curves: Microlensing-aided reverberation mapping
• Further Evidence for the Accretion Disk Origination of the Double-Peaked Broad H$\alpha$ of 3C390.3
• OzDES Reverberation Mapping Program: Lag recovery reliability for 6-year CIV analysis
• Discovering the Mass-Scaled Damping Timescale from Microquasars to Blazars
• Reliable Identification of Binary Supermassive Black Holes from Rubin Observatory Time-Domain Monitoring
• Ensemble power spectral density of SDSS quasars in UV/optical bands
• Modeling the Variability of Active Galactic Nuclei by Infinite Mixture of Ornstein-Uhlenbeck(OU) Processes
• Evidence for a milliparsec-separation Supermassive Binary Black Hole with quasar microlensing
• The X-ray spectral and variability properties of typical radio-loud quasars
• The Relationship Between Simulated Sub-Millimeter and Near-Infrared Images of Sagittarius A* from a Magnetically Arrested Black Hole Accretion Flow
• Characterization of Optical Light Curves of Extreme Variability Quasars Over a ~16-yr Baseline
• A systematic search for changing-look quasars in SDSS-II using difference spectra
• How can the optical variation properties of active galactic nuclei be unbiasedly measured?
• Blazar variability with the Vera C. Rubin Legacy Survey of Space and Time (LSST)
• Constraining AGN Torus Sizes with Optical and Mid-Infrared Ensemble Structure Functions
• On possible proxies of AGN light curves cadence selection in future time domain surveys
• A Mote in Andromeda's Disk: a Misidentified Periodic AGN Behind M31
• Behaviour of the MgII 2798AA Line Over the Full Range of AGN Variability
• Variable classification in the LSST era: Exploring a model for quasi-periodic light curves
• Continuum optical-UV and X-ray variability of AGN: current results and future challenges
• Continuum reverberation mapping of the quasar PG 2130+099
• The effects of Time-Variable Absorption due to Gamma-Ray Bursts In Active Galactic Nuclei Accretion Disks
• Discovering Strongly-lensed QSOs From Unresolved Light Curves
• A Candidate Tidal Disruption Event in a Quasar at z=2.359 from Abundance Ratio Variability
• Testing the linear relationship between black hole mass and variability timescale in low-luminosity AGN at submillimeter wavelengths
• Robust and Accurate Inference via a Mixture of Gaussian and Student's t Errors
• KSwAGS: A Swift X-ray and UV Survey of the Kepler Field. I
• Measuring Lensing Magnification of Quasars by Large Scale Structure using the Variability-Luminosity Relation
• Radio-loud AGN variability from three-dimensional propagating relativistic jets
• Estimation of the size and structure of the broad line region using Bayesian approach
• The SDSS-V Black Hole Mapper Reverberation Mapping Project: Unusual Broad-Line Variability in a Luminous Quasar
• Broad-line region configuration of the supermassive binary black hole candidate PG1302-102 in the relativistic Doppler boosting scenario
• A new timescale-mass scaling for the optical variation of active galactic nuclei across the intermediate-mass to supermassive scales
• A 3.8yr optical quasi-periodic oscillations in blue quasar SDSS J132144+033055 through combined light curves from CSS and ZTF
• The GALEX Time Domain Survey. II. Wavelength-Dependent Variability of Active Galactic Nuclei in the Pan-STARRS1 Medium Deep Survey
• Strong and Rapid X-ray Variability of the Super-Eddington Accreting Quasar SDSS J081456.10+532533.5
• Broad-band spectral energy distribution of 3000 Angstroem break quasars from the Sloan Digital Sky Survey
• Active Galactic Nuclei Discovered in the Kepler Mission
• Latent Stochastic Differential Equations for Modeling Quasar Variability and Inferring Black Hole Properties
• Rapid Optical Variations Correlated with X-rays in the 2015 Second Outburst of V404 Cygni (GS 2023$+$338)
• Estimating Black Hole Masses in Hundreds of Quasars
• Individual optical variability of Active Galactic Nuclei from the MEXSAS2 sample
• Reverberation-mapping of distant quasars: time-lag determination using different methods
• New Clues to Jet Launching: The inner disks in radio loud quasars may be more stable
• X-ray and multi-epoch optical/UV investigations of BAL to non-BAL quasar transformations
• Dust Dynamics in AGN Winds: A New Mechanism For Multiwavelength AGN Variability
• Continuum reverberation mapping of MCG 08-11-011
• AGN Light Echoes and the Accretion Disc Self-Gravity Limit
• Solving the puzzle of discrepant quasar variability on monthly time-scales implied by SDSS and CRTS data sets
• SDSS J1058+5443: A blue quasar does not have optical/NUV broad emission lines
• More variable quasars have stronger emission lines
• Probing the disc-jet coupling in S4 0954+65, PKS 0903-57, & 4C +01.02 with $\gamma$-rays
• Systematic research of low redshift optically selected SDSS Type-2 AGN but with apparent long-term optical variabilities from Catalina Sky Survey, I: data sample and basic results
• Simulating time-varying strong lenses
• Dark Energy Survey Identification of A Low-Mass Active Galactic Nucleus at Redshift 0.823 from Optical Variability
• TESS Shines Light on the Origin of the Ambiguous Nuclear Transient ASASSN-18el
• TD-CARMA: Painless, accurate, and scalable estimates of gravitational-lens time delays with flexible CARMA processes
• Long-term NIR Variability in the UKIDSS Ultra Deep Survey: a new probe of AGN activity at high redshift
• Strongly Lensed Jets, Time Delays, and the Value of H0
• Multi-wavelength Variation Phenomena of PKS 0735+178 on Diverse Timescale
• Black hole virial masses from single-epoch photometry: the miniJPAS test case
• Finding of a population of active galactic nuclei showing a significant luminosity decline in the past $\sim 10^{3-4}$ yrs
• UV Fe II emission model of HE 0413-4031 and its relation to broad-line time delays
• B3\,0749+460A: A New "Changing-Look" Active Galactic Nucleus Associated with X-ray Spectral Slope Variations
• Suspended and restored activities of A Nearby Super Massive Black Hole
• Multi-wavelength properties of three new radio-powerful $z\sim 5.6$ quasi-stellar objects discovered from RACS
• Multiple giant eruptions and X-ray emission in the recoiling AGN/LBV candidate SDSS1133
• Testing the Cosmological Principle: On the Time Dilation of Distant Sources
• Dwarf AGNs from Variability for the Origins of Seeds (DAVOS): Optical Variability of Broad-line Dwarf AGNs from the Zwicky Transient Facility
• Discovery of a new extreme changing-state quasar with 4 mag variation, SDSS J125809.31+351943.0
• Broadband Photometric Reverberation Mapping Analysis on SDSS-RM and Stripe 82 Quasars
• A candidate of binary black hole system in AGN with broad Balmer emission lines having quite different line widths
• Complex Variability of Kepler AGN Revealed by Recurrence Analysis
• A Newborn AGN in a Starforming Galaxy
• Observational nonstationarity of AGN variability: The only way to go is down!
• Optical variability of quasars: a damped random walk
• Variability in Quasar Light Curves: using quasars as standard candles
• More Evidence for the Intermediate Broad Line Region of the Mapped AGN PG 0052+251
• Extreme Variability Quasars in Their Various States. II: Spectral Variation Revealed with Multi-epoch Spectra
• Long-term variability of the composite galaxy SDSS J103911-000057: A candidate of true Type-2 AGN
• The Success of Optical Variability in Uncovering AGNs in Low-stellar Mass Galaxies
• The Sloan Digital Sky Survey Reverberation Mapping Project: Photometric g and i Light Curves
• Strong Lensed QSOs with Variability Detectable by LSST: How many are there?
• Temperature Fluctuations in Quasar Accretion Discs from Spectroscopic Monitoring Data
• A Sample Bias in Quasar Variability Studies
• Examining AGN UV/Optical Variability Beyond the Simple Damped Random Walk. II. Insights from 22 Years Observations of SDSS, PS1 and ZTF
• Using Gaussian Processes to detect AGN flares
• FORECASTOR -- I. Finding Optics Requirements and Exposure times for the Cosmological Advanced Survey Telescope for Optical and UV Research mission
• Stochastic modeling of the time variability of ALMA calibrators
• Ensemble Variability Properties of Active Galactic Nuclei in the SDSS DR17
• The Awakening Beast in the Seyfert 1 Galaxy KUG 1141+371 I
• Reddening and the Shape of the Variable Component of the Continua of Active Galactic Nuclei From the Optical to the Far Ultraviolet. I
• AGNet: Weighing Black Holes with Deep Learning
• Temperature Profiles of Accretion Disks in Luminous Active Galactic Nuclei derived from Ultraviolet Spectroscopic Variability
• On the Origin of the Dramatic Spectral Variability of WPVS 007
• Composite reverberation mapping
• An X-ray View of the Ambiguous Nuclear Transient AT2019pev
• Observational window effects on multi-object Reverberation Mapping
• Optical polarization of stellar-fed active and quiescent supermassive black holes
• Periodic variability of the z=2.0 quasar QSO B1312+7837
• Swift Monitoring Observations of Mrk 231: Detection of Ultraviolet Variability
• Optical spectral index - luminosity relation for the 17 mapped Palomar-Green quasars
• A Systematic Search for Active Galactic Nucleus Flares in ZTF Data Release 23
• Appearance of an accretion disk perturbed by fractional Brownian Motion density
• The Variability of the Narrow-line Seyfert 1 Galaxies from the PanSTARRS's View
• A novel approach to study the variability of NGC 5548
• The relation between quasars' optical spectra and variability
• Brightness and colour variability in NLSy1s
• Probing the rest-frame wavelength dependence of quasar variability : Insights from the Zwicky Transient Facility Survey
• Joint Modeling of Quasar Variability and Accretion Disk Reprocessing using Latent Stochastic Differential Equations
• Rapidly accreting black hole of the Lyα-luminous quasar PSO J006.1240+39.2219
• Standardizing reverberation-measured Mg II time-lag quasars, by using the radius-luminosity relation, and constraining cosmological model parameters
• Photometric Selection of type 1 Quasars in the XMM-LSS Field with Machine Learning and the Disk-Corona Connection
• High frequency breaks in optical active galactic nuclei power spectral density
• Discovery of two quasars at $z=5$ from the OGLE Survey
• Seeking Neutrino Emission from AGN through Temporal and Spatial Cross Correlation
• Accretion disc reverberation mapping of the quasar 3C 273
• HALO I: Photometric continuum reverberation mapping of Fairall 9
• Continuum polarization reverberation mapping of AGNs
• Scalable and Robust Multiband Modeling of AGN Light Curves in Rubin-LSST
• Light-curve instabilities of Beta Lyrae observed by the BRITE satellites
• Processing GOTO data with the Rubin Observatory LSST Science Pipelines II: Forced Photometry and light curves
• Time delay estimation in unresolved lensed quasars
• Six Maxims of Statistical Acumen for Astronomical Data Analysis
• Optical selection of quasars: SDSS and LSST
• Long-term optical flux and colour variability in quasars
• Sources of confusion noise in the infrared wavelength range
• Searching for supermassive black holes binaries within SRG/eROSITA-De I: Properties of the X-ray selected candidates
• Identifying massive black hole binaries via light curve variability in optical time-domain surveys
• A Statistical Analysis of Crab Pulsar Giant Pulse Rates
• Detection of quasars in the time domain
• Amoeba: An AGN Model of Optical Emissions Beyond steady-state Accretion discs
• Harnessing Unresolved Lensed Quasars: The Mathematical Foundation of the Fluctuation Curve
• Predicting High-magnification Events in Microlensed Quasars in the Era of LSST using Recurrent Neural Networks
• The Feasibility and Flexibility of Selecting Quasars by Variability Using Ensemble Machine Learning Algorithms
• SDSSJ14584479+3720215: A Benchmark JHK Blazar Light Curve from the 2MASS Calibration Scans
• Decadal Variability Survey in MACSJ1149
• AGN variability in the age of VRO
• Untangling the Complex Nature of AGN Variability with Fairall 9
• The ensemble broad-frequency power spectrum of Stripe-82 quasars from multiple surveys
• A Unified Interpretation of Supernova, GRB, and QSO Time Dilation Signals in a Generalized Cosmological Time Framework
• Discovery of the Asymmetric Effect in the Response of Photoionization Gas
• The Sloan Digital Sky Survey Reverberation Mapping Project: UV-Optical Accretion Disk Measurements with Hubble Space Telescope
• A Comparison of Properties of Quasars with and without Rapid Broad Absorption Line Variability
• Searching for unresolved massive black hole pairs through AGN photometric variability
• Quasar Microlensing Models with Constraints on the Quasar Light Curves
• Optical variability of eight FRII-type quasars with 13-yr photometric light curves
• Reprocessing Models for the Optical Light Curves of Hypervariable Quasars from the Sloan Digital Sky Survey Reverberation Mapping Project
• On the time delay evolution of five Active Galactic Nuclei
• Simulating quasar microlensing light curves: High magnification events
• Changing Look AGN: A study of Optical/UV and the Highly Ionized Fe K$\alpha$ X-ray Line Flux Variations Using Photo-Ionization Simulations
• The variational slope of quasar light curves is not a distance indicator
• Massive black holes in the first billion years with JWST
• Optical Variability as a Probe of Hidden Nuclear Activity in Type 2 AGNs
• Optical Variability Structure Function of Low-Luminosity AGN using ATLAS Lightcurves
• BASS XXX: Distribution Functions of DR2 Eddington-ratios, Black Hole Masses, and X-ray Luminosities
• Variability Selected Active Galactic Nuclei from ASAS-SN Survey: Constraining the Low Luminosity AGN Population
• Extreme variability quasars from the Sloan Digital Sky Survey and the Dark Energy Survey
• AGN BLR structure, luminosity and mass from combined Reverberation Mapping and Optical Interferometry observations
• AGILE: an end-to-end Rubin-LSST simulation of AGNs, galaxies, and stars I. Software description and first data release
• SRG/eROSITA-SDSS view on the relation between X-ray and UV emission for quasars
• A Convolutional Neural Network for the Recovery of Transfer Functions From Velocity-Resolved Reverberation Mapping Data
• The shortest detected intra-day variability of active galactic nuclei in TESS survey
• Machine Learning Identification of Gravitationally Microlensed Gamma-Ray Bursts
• Random walks around black holes and low-frequency X-ray variability
• Seeing through the dust: Unraveling near-infrared variability in type 2 active galactic nuclei
• SDSS J153231.80+420342.7: a triple black hole candidate with a close binary black hole
• The possible long-term periodic variability of the extremely luminous quasar WISE J090924.01+000211.1
• Identifications of RR Lyrae stars and Quasars from the simulated data of Mephisto-W Survey