Estimating Black Hole Masses in Hundreds of Quasars

Abstract

We explore the practical feasibility of AGN broad-band reverberation mapping and present first results. We lay out and apply a rigorous approach for stochastic reverberation mapping of unevenly sampled multi-broad-band flux measurements, assuming that the broad-line region (BLR) line flux is contributing up to 15 % in some bands, and is directly constrained by one spectroscopical epoch. The approach describes variations of the observed flux as the continuum, modeled as a stochastic Gaussian process, and emission line contribution, modeled as a scaled, smoothed and delayed version of the continuum. This approach is capable not only to interpolate in time between measurements, but also to determine confidence limits on continuum -- line emission delays. This approach is applied to SDSS observations in 'Stripe 82' (S82) providing flux measurements precise to 2 % at $\sim$ 60 epochs over $\sim$ 10 years. The strong annual variations in the epoch sampling prove a serious limitation in practice. Also, suitable redshift ranges must be identified, where strong broad emission line contribute to one filter, but not to another. Through generating and evaluating problem-specific mock data, we verify that S82-like data can constrain ${\tau }_{\mathrm{delay}}$ for a simple transfer function model. In application to real data, we estimate ${\tau }_{\mathrm{delay}}$ for 323 AGN with $0.225<z<0.846$, combining information for different objects through the ensemble-scaling relationships for BLR size and BH mass. Our analysis tentatively indicates a 1.7 times larger BLR size of H$\alpha$ and MgII compared to Kaspi2000 and Vestergaard2002, but the seasonal data sampling casts doubt on the robustness of the inference.

References in corpus (37)

• emcee: The MCMC Hammer
• The Sloan Digital Sky Survey: Technical Summary
• Reverberation Measurements for 17 Quasars and the Size-Mass-Luminosity Relations in Active Galactic Nuclei
• Composite Quasar Spectra From the Sloan Digital Sky Survey
• Central Masses and Broad-Line Region Sizes of Active Galactic Nuclei. II. A Homogeneous Analysis of a Large Reverberation-Mapping Database
• A Catalog of Quasar Properties from SDSS DR7
• 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
• 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
• 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 Sloan Digital Sky Survey Quasar Catalog IV. Fifth Data Release
• The Sloan Digital Sky Survey-II Supernova Survey: Technical Summary
• Reverberation Mapping of High-Luminosity Quasars: First Results
• Determining Central Black Hole Masses in Distant Active Galaxies
• 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
• Is Quasar Optical Variability a Damped Random Walk?
• Efficient Photometric Selection of Quasars from the Sloan Digital Sky Survey: II. ~1,000,000 Quasars from Data Release Six
• A Description of Quasar Variability Measured Using Repeated SDSS and POSS Imaging
• On the Reliability of Cross Correlation Function Lag Determinations in Active Galactic Nuclei
• The Lick AGN Monitoring Project: Reverberation Mapping of Optical Hydrogen and Helium Recombination Lines
• The SDSS Coadd: 275 deg^2 of Deep SDSS Imaging on Stripe 82
• Selecting Quasars by their Intrinsic Variability
• Optimal Time-Series Selection of Quasars
• Galactic Stellar Populations in the Era of SDSS and Other Large Surveys
• Photometric AGN reverberation mapping - an efficient tool for BLR sizes, black hole masses and host-subtracted AGN luminosities
• The Color Variability of Quasars
• Application of Stochastic Modeling to Analysis of Photometric Reverberation Mapping Data
• Assessment of stochastic and deterministic models of 6304 quasar lightcurves from SDSS Stripe 82
• Measuring Quasar Variability with Pan-STARRS1 and SDSS
• Broad Band Photometric Reverberation Mapping of NGC 4395
• Photometric Reverberation Mapping of the Broad Emission Line Region in Quasars
• Quasar Cartography: from Black Hole to Broad Line Region Scales
• On the Performance of Quasar Reverberation Mapping in the Era of Time-Domain Photometric Surveys

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