Slow-Roll Inflation Preceded by a Topological Defect Phase \`a la
  Chaplygin Gas
  We present a simple toy model corresponding to a network of frustrated
topological defects of domain walls or cosmic strings that exist previous to
the standard slow-roll inflationary era of the universe. Such a network (i) can
produce a slower inflationary era than that of the standard scenario if it
corresponds to a network of frustrated domain walls or (ii) can induce a
vanishing universal acceleration; i.e., the universe would expand at a constant
speed, if it corresponds to a network of frustrated cosmic strings red. Those
features are phenomenologically modeled by a Chaplygin gas that can interpolate
between a network of frustrated topological defects and a de Sitter-like or a
power-law inflationary era. We show that this scenario can alleviate the
quadruple anomaly of the cosmic microwave background spectrum. Using the method
of the Bogoliubov coefficients, we obtain the spectrum of the gravitational
waves as would be measured today for the whole range of frequencies. We comment
on the possible detection of this spectrum by the planned detectors like BBO
and DECIGO.
