Cosmological Imprints of a Generalized Chaplygin Gas Model for the Early   Universe
  We propose a phenomenological model for the early universe where there is a smooth transition between an early "quintessence" phase and a radiation dominated era. The matter content is modelled by an appropriately modified Chaplygin gas for the early universe. We constrain the model observationally by mapping the primordial power spectrum of the scalar perturbations to the latest data of WMAP7. We compute as well the spectrum of the primordial gravitational waves as would be measured today. We show that the high frequencies region of the spectrum depends on the free parameter of the model and most importantly this region of the spectrum can be within the reach of future gravitational waves detectors. 
Mariam Bouhmadi-Lopez, Pisin Chen, Yen-Wei Liu
astro-ph.CO gr-qc