This paper explores the effects of stellar evolution uncertainties
(particularly the properties of thermally pulsating AGB stars, but
also metallicity and the IMF) on quantities derived through stellar
population modeling like age, mass, and star-formation rate. From
computing expected colors of LMC star clusters the authors conclude
that the temperature and luminosity of the TP-AGB phase could vary by
as much as +-0.2 dex and +-0.4 dex respectively, and so they allow
these parameters to vary in their stellar population fitting. The
plot above shows 68% and 95% likelihood contours for the derived
properties for a bright z~2 quiescent galaxy, with probability
distributions (blue line: AGB star uncertainties included; black: not
included) in the top panel. Interestingly, the degeneracies between
the AGB parameters and derived quantities are weak at best, and the
uncertainties don't seem to increase much (blue vs. black curves).
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