On the Performance of Quasar Reverberation Mapping in the Era of Time-Domain Photometric Surveys

TL;DR

This study uses simulations to evaluate how well upcoming broad-band photometric surveys, like LSST, can measure quasar BLR sizes and black hole masses across various conditions and redshifts, promising significant advancements in AGN research.

Contribution

It demonstrates that photometric surveys can accurately determine BLR size-luminosity relations and black hole masses, expanding capabilities beyond traditional spectroscopic methods.

Findings

BLR size-luminosity relation slope can be measured with a few percent accuracy.

Over 100,000 time-delay measurements are feasible for key emission lines.

Photometric surveys will improve black hole mass estimates and calibration of scaling relations.

Abstract

We quantitatively assess, by means of comprehensive numerical simulations, the ability of broad-band 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, of order a few percent, over a broad luminosity range and out to $z\sim 3$. In particular, major emission lines for which the BLR size can be reliably measured with LSST include H$\alpha$, MgII $\lambda 2799$, CIII] $\lambda 1909$, CIV $\lambda 1549$, and Ly$\alpha$, amounting to a total of $\gtrsim 10^5$ 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 AGN 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.