Effect of dark energy sound speed and equation of state on CDM power spectrum

We have studied the influence of equation of state w, and effective sound speed ce of the dark energy perturbations on the cold dark matter (CDM) power spectrum. We have considered different cases of the equation of state and the effective sound speed, and the CDM power spectrum is found to be generically suppressed in these cases as compared to the ΛCDM model. The suppression at different length scales depends on the value of ω and ce, and the effect of different ω is profoundly seen at all length scales. The influence of sound speed is significantly seen only at the intermediate length scales, and is negligible at scales very much larger and smaller than the Hubble scale.