Evidence for Cosmic Acceleration is Robust to Observed Correlations
  Between Type Ia Supernova Luminosity and Stellar Age
  Type Ia Supernovae (SNe Ia) are powerful standardizable candles for
constraining cosmological models and provided the first evidence of the
accelerated expansion of the universe. Their precision derives from empirical
correlations, now measured from $>1000$ SNe Ia, between their luminosities,
light-curve shapes, colors and most recently with the stellar mass of their
host galaxy. As mass correlates with other galaxy properties, alternative
parameters have been investigated to improve SN Ia standardization though none
have been shown to significantly alter the determination of cosmological
parameters. We re-examine a recent claim, based on 34 SN Ia in nearby passive
host galaxies, of a 0.05 mag/Gyr dependence of standardized SN Ia luminosity on
host age which if extrapolated to higher redshifts, would be a bias up to 0.25
mag, challenging the inference of dark energy. We reanalyze this sample of
hosts using both the original method and a Bayesian hierarchical model and find
after a fuller accounting of the uncertainties the significance of a dependence
on age to be $\leq2\sigma$ and $\sim1\sigma$ after the removal of a single
poorly-sampled SN Ia. To test the claim that a trend seen in old stellar
populations can be applied to younger ages, we extend our analysis to a larger
sample which includes young hosts. We find the residual dependence of host age
(after all standardization typically employed for cosmological measurements) to
be consistent with zero for 254 SNe Ia from the Pantheon sample, ruling out the
large but low significance trend seen in passive hosts.
