The Sloan Digital Sky Survey Reverberation Mapping Project: Comparison of Lag Measurement Methods with Simulated Observations

Abstract

We investigate the performance of different methodologies that measure the time lag between broad-line and continuum variations in reverberation mapping data using simulated light curves that probe a range of cadence, time baseline, and signal-to-noise ratio in the flux measurements. We compare three widely-adopted lag measuring methods: the Interpolated Cross-Correlation Function (ICCF), the z-transformed Discrete Correlation Function (ZDCF) and the MCMC code JAVELIN, for mock data with qualities typical of multi-object spectroscopic reverberation mapping (MOS-RM) surveys that simultaneously monitor hundreds of quasars. We quantify the overall lag detection efficiency, the rate of false detections, and the quality of lag measurements for each of these methods and under different survey designs (e.g., observing cadence and depth) using mock quasar light curves. Overall JAVELIN and ICCF outperform ZDCF in essentially all tests performed. Compared with ICCF, JAVELIN produces higher quality lag measurements, is capable of measuring more lags with timescales shorter than the observing cadence, is less susceptible to seasonal gaps and S/N degradation in the light curves, and produces more accurate lag uncertainties. We measure the Hbeta broad-line region size-luminosity (R-L) relation with each method using the simulated light curves to assess the impact of selection effects of the design of MOS-RM surveys. The slope of the R-L relation measured by JAVELIN is the least biased among the three methods, and is consistent across different survey designs. These results demonstrate a clear preference for JAVELIN over the other two non-parametric methods for MOS-RM programs, particularly in the regime of limited light curve quality as expected from most MOS-RM programs.

arXiv comment22 pages, 34 figures, Accepted for publication in the Astrophysical Journal

References in corpus (59)

• emcee: The MCMC Hammer
• Reverberation Measurements for 17 Quasars and the Size-Mass-Luminosity Relations in Active Galactic Nuclei
• A Catalog of Quasar Properties from SDSS DR7
• Some Aspects of Measurement Error in Linear Regression of Astronomical Data
• Determining Central Black Hole Masses in Distant Active Galaxies and Quasars. II. Improved Optical and UV Scaling Relationships
• The SDSS Quasar Survey: Quasar Luminosity Function from Data Release Three
• The Low-Luminosity End of the Radius-Luminosity Relationship for Active Galactic Nuclei
• The Relationship Between Luminosity and Broad-Line Region Size in Active Galactic Nuclei
• Are the Variations in Quasar Optical Flux Driven by Thermal Fluctuations?
• Modeling the Time Variability of SDSS Stripe 82 Quasars as a Damped Random Walk
• Central Masses and Broad-Line Region Sizes of Active Galactic Nuclei: I. Comparing the Photoionization and Reverberation Techniques
• On Uncertainties in Cross-Correlation Lags and the Reality of Wavelength-Dependent Continuum Lags in Active Galactic Nuclei
• The Radius-Luminosity Relationship for Active Galactic Nuclei: The Effect of Host-Galaxy Starlight on Luminosity Measurements II. The Full Sample of Reverberation-Mapped AGNs
• The cosmological evolution of quasar black-hole masses
• Reverberation Mapping of High-Luminosity Quasars: First Results
• The Radius-Luminosity Relationship for Active Galactic Nuclei: The Effect of Host-Galaxy Starlight on Luminosity Measurements
• Quantifying Quasar Variability As Part of a General Approach To Classifying Continuously Varying Sources
• Keplerian Motion of Broad-Line Region Gas as Evidence for Supermassive Black Holes in Active Galactic Nuclei
• An Alternative Approach To Measuring Reverberation Lags in Active Galactic Nuclei
• A Description of Quasar Variability Measured Using Repeated SDSS and POSS Imaging
• Evidence for Supermassive Black Holes in Active Galactic Nuclei from Emission-Line Reverberation
• Comparing Single-Epoch Virial Black Hole Mass Estimators for Luminous Quasars
• Introduction to astroML: Machine Learning for Astrophysics
• The Sloan Digital Sky Survey quasar catalog: ninth data release
• Kepler Observations of Rapid Optical Variability in Active Galactic Nuclei
• Black Hole Growth to z = 2 - I: Improved Virial Methods for Measuring M_BH and L/L_Edd
• The Sloan Digital Sky Survey Reverberation Mapping Project: H$\alpha$ and H$\beta$ Reverberation Measurements From First-year Spectroscopy and Photometry
• Estimating Black Hole Masses in Active Galactic Nuclei Using the MgII 2800 Emission Line
• The Sloan Digital Sky Survey Reverberation Mapping Project: Technical Overview
• The Structure of the Broad Line Region in AGN: I. Reconstructed Velocity-Delay Maps
• The First Swift Intensive AGN Accretion Disk Reverberation Mapping Survey
• On Quasar Masses and Quasar Host Galaxies
• The Sloan Digital Sky Survey Reverberation Mapping Project: Velocity Shifts of Quasar Emission Lines
• The Demographics of Broad Line Quasars in the Mass-Luminosity Plane II. Black Hole Mass and Eddington Ratio Functions
• Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. V. A New Size-Luminosity Scaling Relation for the Broad-Line Region
• A Stochastic Model for the Luminosity Fluctuations of Accreting Black Holes
• Are the Variability Properties of the Kepler AGN Light Curves Consistent with a Damped Random Walk?
• The Sloan Digital Sky Survey Reverberation Mapping Project: First Broad-line Hbeta and MgII Lags at z>~0.3 from six-Month Spectroscopy
• The Kepler Light Curves of AGN: A Detailed Analysis
• Pan-STARRS1 variability of XMM-COSMOS AGN. II. Physical correlations and power spectrum analysis
• The Sloan Digital Sky Survey Reverberation Mapping Project: Initial CIV Lag Results from Four Years of Data
• Limitations on the recovery of the true AGN variability parameters using Damped Random Walk modeling
• The Mass of the Central Black Hole in the Seyfert Galaxy NGC 4151
• Reverberation Mapping of Luminous Quasars at High-z
• Accretion Disc Time Lag Distributions: Applying CREAM to Simulated AGN Light Curves
• The Sloan Digital Sky Survey Reverberation Mapping Project: Accretion-Disk Sizes from Continuum Lags
• Can reverberation-measured quasars be used for cosmology?
• Extracting Information from AGN Variability
• The Sloan Digital Sky Survey Reverberation Mapping Project: Low-Ionization Broad-Line Widths and Implications for Virial Black Hole Mass Estimation
• Simulations of the OzDES AGN Reverberation Mapping Project
• Improved AGN light curve analysis with the z-transformed discrete correlation function
• A Degeneracy in DRW Modelling of AGN Light Curves
• How far is quasar UV/optical variability from damped random walk at low frequency?
• Scattering Polarization and Hanle Effect in Stellar Atmospheres with Horizontal Inhomogeneities
• Constraints on the broad line region from regularized linear inversion: Velocity-delay maps for five nearby active galactic nuclei
• Stability of the Broad Line Region Geometry and Dynamics in Arp 151 Over Seven Years
• Methods of Reverberation Mapping. I. Time-lag Determination by Measures of Randomness
• A Method to Measure the Unbiased Decorrelation Timescale of the AGN Variable Signal from Structure Functions
• The Sloan Digital Sky Survey Reverberation Mapping Project: Composite Lags at $z\lesssim 1$

Cited by in corpus (21)

• The Sixteenth Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra
• The Sloan Digital Sky Survey Reverberation Mapping Project: Estimating Masses of Black Holes in Quasars with Single-Epoch Spectroscopy
• The Sloan Digital Sky Survey Reverberation Mapping Project: Initial CIV Lag Results from Four Years of Data
• The Sloan Digital Sky Survey Reverberation Mapping Project: MgII Lag Results from Four Years of Monitoring
• The Sloan Digital Sky Survey Reverberation Mapping Project: The H$\beta$ Radius-Luminosity Relation
• Accretion Disk Sizes from Continuum Reverberation Mapping of AGN Selected from the ZTF Survey
• On Reverberation Mapping Lag Uncertainties
• Time Delay of MgII Emission Response for the Luminous Quasar HE 0435-4312: Towards Application of High-Accretor Radius-Luminosity Relation in Cosmology
• Current and future applications of Reverberation-mapped quasars in Cosmology
• OzDES Reverberation Mapping Program: The first Mg II lags from five years of monitoring
• Multi-Wavelength Monitoring and Reverberation Mapping of a Changing Look Event in the Seyfert Galaxy NGC 3516
• Scatter Analysis Along the Multidimensional Radius-Luminosity Relations for Reverberation-Mapped Mg II Sources
• OzDES Reverberation Mapping Program: Lag recovery reliability for 6-year CIV analysis
• 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
• Joint ALMA/X-ray monitoring of the radio-quiet type 1 AGN IC 4329A
• Multi-wavelength Variation Phenomena of PKS 0735+178 on Diverse Timescale
• Observational window effects on multi-object Reverberation Mapping
• Revisiting the Continuum Reverberation Lags in the AGN PKS 0558-504
• OzDES Reverberation Mapping Program: Stacking analysis with H$\beta$, Mg II and C IV
• Intensive X-ray/UVOIR continuum reverberation mapping of the Seyfert AGN MCG+08-11-11
• The Sloan Digital Sky Survey Reverberation Mapping Project: UV-Optical Accretion Disk Measurements with Hubble Space Telescope