Dynamical Modeling of the C iv Broad Line Region of the z = 2.805 Multiply Imaged Quasar SDSS J2222+2745

Abstract

We present the first ever models of a broad line region (BLR) at the peak of active galactic nucleus (AGN) activity using the multiply imaged z = 2.805 quasar SDSS J2222+2745. The modeled data consist of monthly spectra covering the broad C iv emission line over a 5.3 yr baseline. The models suggest a thick disk BLR that is inclined by ∼40° to the observer’s line of sight and with an emissivity weighted median radius of rmedian=33.0−2.1+2.4 light days. The kinematics are dominated by near-circular Keplerian motion with the remainder inflowing. The rest-frame lag one would measure from the models is τmedian=36.4−1.8+1.8 days, which is consistent with measurements based on cross-correlation. We show a possible geometry and transfer function based on the model fits and find that the model-produced velocity-resolved lags are consistent with those from cross-correlation. We measure a black hole mass of log10(MBH/M⊙)=8.31−0.06+0.07 , which requires a scale factor of log10(fmean,σ)=0.20−0.07+0.09 . This is the most precise M BH measurement for any AGN at cosmological distances and it demonstrates that the precision required for BH-host coevolution studies is attainable.