Simulations of the OzDES AGN reverberation mapping project

Abstract

As part of the Australian spectroscopic dark energy survey (OzDES) we are carrying out a large-scale reverberation mapping study of ≥500 quasars over five years in the 30 deg2 area of the Dark Energy Survey (DES) supernova fields. These quasars have redshifts ranging up to 4 and have apparent AB magnitudes between 16.8 mag < r < 22.5 mag. The aim of the survey is to measure time lags between fluctuations in the quasar continuum and broad emission-line fluxes of individual objects in order to measure black hole masses for a broad range of active galactic nuclei (AGN) and constrain the radius–luminosity (R–L) relationship. Here we investigate the expected efficiency of the OzDES reverberation mapping campaign and its possible extensions. We expect to recover lags for ∼35–45 per cent of the quasars. AGN with shorter lags and greater variability are more likely to yield a lag measurement, and objects with lags ≲6 months or ∼1 yr are expected to be recovered the most accurately. The baseline OzDES reverberation mapping campaign is predicted to produce an unbiased measurement of the R–L relationship parameters for H β, Mg ii λ2798, and C iv λ1549. Extending the baseline survey by either increasing the spectroscopic cadence, extending the survey season, or improving the emission-line flux measurement accuracy will significantly improve the R–L parameter constraints for all broad emission lines.