On the performance of quasar reverberation mapping in the era of time-domain photometric surveys

We quantitatively assess, by means of comprehensive numerical simulations, the ability of broadband photometric surveys to recover the broad emission line region (BLR) size in quasars under various observing conditions and for a wide range of object properties. Focusing on the general characteristics of the Large Synoptic Survey Telescope (LSST), we find that the slope of the size-luminosity relation for the BLR in quasars can be determined with unprecedented accuracy, on the order of a few percent, over a broad luminosity range and out to z ∼ 3. In particular, major emission lines for which the BLR size can be reliably measured with LSST include Hα, Mg II λ2799, C III] λ1909, C IV λ1549, and Lyα, amounting to a total of ≳ 10⁵ time-delay measurements for all transitions. Combined with an estimate for the emission line velocity dispersion, upcoming photometric surveys will facilitate the estimation of black hole masses in active galactic nuclei over a broad range of luminosities and redshifts, allow for refined calibrations of BLR size-luminosity-redshift relations in different transitions, as well as lead to more reliable cross-calibration with other black hole mass estimation techniques.