Tracing the History of Recent Bulge Star Formation in Active Galactic
  Nuclei
  We examine the relation between black hole accretion and bulge star formation
as a function of look-back time (tau) in 20,541 obscured AGNs (with redshifts
<z> ~ 0.1 and bolometric luminosities L_Bol ~ 10^43--10^45 erg s^-1) optically
selected from the Sloan Digital Sky Survey (SDSS). To quantify the most
recently formed stars with ages less than typical AGN lifetimes, we estimate
the differentiated specific star formation rate (SSFR_tau) based on population
synthesis analysis. Eddington ratio (lambda) is inferred using [O III]5007
luminosity and stellar velocity dispersion as proxies for L_Bol and black hole
mass respectively. We find that when tau < tau_0, SDSS AGNs follow a power law:
lambda \propto (SSFR_tau)^1.0-1.1; the relation flattens out when tau > tau_0.
The threshold timescale tau_0 is ~ 0.1 (~ 1) Gyr in young (old) bulges. The
scatter in the power laws is dominated by observational uncertainties. These
results may provide useful constraints on models explaining the correlations
between AGN activity and bulge star formation.
