Investigating the Variable Continuum Lags in PG 2130+099

Abstract Broadband photometric reverberation mapping (RM) provides a measure of the size of the continuum-emitting region in active galactic nuclei (AGN). Previous monitoring campaigns of PG 2130+099 disagree as to whether the continuum-emitting region size is consistent with that predicted for a standard optically thick and geometrically thin accretion disk. We present ∼6 months of observations from several robotic telescopes, providing the highest-cadence and widest-wavelength coverage photometric RM study of PG 2130+099 to date. Our results indicate that the inferred size of the continuum-emitting region in PG 2130+099, like many recently observed AGN, is larger than the simplest predictions for an irradiated geometrically thin, optically thick accretion disk. We also perform a flux–flux analysis, finding a variable spectrum broadly consistent with a disk, and a constant component with enhanced i -band emission, potentially due to H α . We find some evidence of increasing lag with luminosity, but previous lag measurements are too uncertain to be definitive.