LAUSR

We measure the optical variability in ∼16500 low-redshift (z ∼ 0.1) galaxies to map the relations between AGN activity and galaxy stellar mass, specific star-formation rate, half-light radius and bulge-to-total ratio. To do this, we use a reduced χ2 variability measure on > 10 epoch lightcurves from the Zwicky Transient Facility and combine with spectroscopic data and derived galaxy parameters from the Sloan Digital Sky Survey. We find that below stellar mass of 1011 M⊙, galaxies classed as star-forming via the BPT diagram have higher mean variablities than AGN or composite galaxies. Revealingly, the highest mean variabilities occur in star-forming galaxies in narrow range of specific star-formation -11 < log(sSFR/yr−1) < -10. In very actively star-forming galaxies (log(sSFR/yr−1) > -10), the reduced variability implies a lack of instantaneous correlation with star-formation rate. Our results may indicate that a high level of variability, and thus black hole growth, acts as a precursor for reduced star-formation, bulge growth, and revealed AGN-like emission lines. These results add to the mounting evidence that optical variability can act as a viable tracer for low-mass AGNs and that such AGNs can strongly affect their host galaxy.