  Amorphous materials have a rich relaxation spectrum, which is usually
described in terms of a hierarchy of relaxation mechanisms. In this work, we
investigate the local dynamic modulus spectra in a model glass just above the
glass transition temperature by performing a mechanical spectroscopy analysis
with molecular dynamics simulations. We find that the spectra, at the local as
well as on the global scale, can be well described by the Cole-Davidson formula
in the frequency range explored with simulations. Surprisingly, the
Cole-Davidson stretching exponent does not change with the size of the local
region that is probed. The local relaxation time displays a broad distribution,
as expected based on dynamic heterogeneity concepts, but the stretching is
obtained independently of this distribution. We find that the size dependence
of the local relaxation time and moduli can be well explained by the elastic
shoving model.
