Multiple populations within globular clusters in Early-type galaxies
  Exploring their effect on stellar initial mass function estimates
  It is now well-established that most (if not all) ancient globular clusters
host multiple popula- tions, that are characterised by distinct chemical
features such as helium abundance variations along with N-C and Na-O
anti-correlations, at fixed [Fe/H]. These very distinct chemical fea- tures are
similar to what is found in the centres of the massive early-type galaxies and
may influence measurements of the global properties of the galaxies.
Additionally, recent results have suggested that M/L variations found in the
centres of massive early-type galaxies might be due to a bottom-heavy stellar
initial mass function. We present an analysis of the effects of globular
cluster-like multiple populations on the integrated properties of early-type
galaxies. In particular, we focus on spectral features in the integrated
optical spectrum and the global mass-to-light ratio that have been used to
infer variations in the stellar initial mass function. To achieve this we
develop appropriate stellar population synthesis models and take into account,
for the first time, an initial-final mass relation which takes into
consideration a varying He abundance. We conclude that while the multiple
populations may be present in massive early-type galaxies, they are likely not
responsible for the observed variations in the mass- to-light ratio and IMF
sensitive line strengths. Finally, we estimate the fraction of stars with
multiple populations chemistry that come from disrupted globular clusters
within massive ellipticals and find that they may explain some of the observed
chemical patterns in the centres of these galaxies.
