Modeling reverberation mapping data I: improved geometric and dynamical models and comparison with cross-correlation results

摘要

We present an improved and expanded simply parameterized phenomenologicalmodel of the broad line region (BLR) in active galactic nuclei (AGN) formodeling reverberation mapping data. By modeling reverberation mapping datadirectly, we can constrain the geometry and dynamics of the BLR and measure theblack hole mass without relying on the normalization factor needed in thetraditional analysis. For realistic simulated reverberation mapping datasets ofhigh-quality, we can recover the black hole mass to $0.05-0.25$ dex uncertaintyand distinguish between dynamics dominated by elliptical orbits and inflowinggas. While direct modeling of the integrated emission line light curve allowsfor measurement of the mean time lag, other details of the geometry of the BLRare better constrained by the full spectroscopic dataset of emission lineprofiles. We use this improved model of the BLR to explore possible sources ofuncertainty in measurements of the time lag using cross-correlation function(CCF) analysis and in measurements of the black hole mass using the virialproduct. Sampling the range of geometries and dynamics in our model of the BLRsuggests that the theoretical uncertainty in black hole masses measured usingthe virial product is on the order of 0.25 dex. These results support the useof the CCF to measure time lags and the virial product to measure black holemasses when direct modeling techniques cannot be applied, provided theuncertainties associated with the interpretation of the results are taken intoaccount.