Abstract :
The variable emission from AGN can be used to probe the structure of accretion disks via continuum reverberation mapping. In low-luminosity AGN, the inferred disk sizes from inter-band delays are 3x times larger than expected from standard disk theory, although this size discrepancy may decrease in more luminous AGN. Using NASA/ATLAS as a precursor to LSST, we analysed light curves of 10,000 bright quasars at redshift 0.3–2.5 in the largest reverberation study to date. We test various large-scale pipeline procedures on real data, finding a stacked approached greatly improves delay measurements. Here, we find the size discrepancy persists in our luminous sample, with a complex dependence on rest-frame wavelength that suggests contamination of variable continuum emission by diffuse broad line region processes is widespread. We test delay behaviour against a variety of quasar properties finding longer lags in quasars with: higher Eddington ratios, redder colours, stronger optical Fe II EWs, higher iron ratios (both UV Fe II/Mg II and optical Fe II /H β), C IV broad absorption troughs, and lower C IV blueshift.
