Direct Constraints on the Impact of TP-AGB Stars on the SED of Galaxies
  from Near-Infrared Spectroscopy
  We present new spectro-photometric NIR observations of 16 post-starburst
galaxies especially designed to test for the presence of strong carbon features
of thermally pulsing AGB (TP-AGB) stars, as predicted by recent models of
stellar population synthesis. Selection based on clear spectroscopic optical
features indicating the strong predominance of stellar populations with ages
between 0.5 and 1.5 Gyr and redshift around 0.2 allows us to probe the spectral
region that is most affected by the carbon features of TP-AGB stars
(unaccessible from the ground for z~0 galaxies) in the evolutionary phase when
their impact on the IR luminosity is maximum. Nevertheless, none of the
observed galaxies display such features. Moreover the NIR fluxes relative to
optical are consistent with those predicted by the original Bruzual & Charlot
(2003) models, where the impact of TP-AGB stars is much lower than has been
recently advocated.
