2011/04/24 by R. Ansari, Rizwan Ul Haq Ansari, Ansari, Rizwan Ul Haq +2
Earth and Planetary Sciences · Economics, Econometrics and Finance · Physics and Astronomy · #Complex Systems and Time Series Analysis #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #Geophysics and Gravity Measurements #astro-ph.CO #gr-qc
paper · pdf · doi:10.48550/arxiv.1104.4609
17 pages, 14 figures
arxiv created 2011/04/24 · openalex publication_date 2011/04/24 · arxiv updated 2011/04/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The behavior of perturbation in scalar field dark energy and its consequent effect on the cold dark matter (CDM) power spectrum is well understood to be governed by the equation of state (EOS) parameter and the effective speed of sound (ESS) of dark energy. In this paper, we investigate whether dark energy models whose ESS are epoch dependent leaves any distinct imprints on the large scale CDM power spectrum. In particular, we compare the cases where the ESS is decreasing with time with those where it increases. The CDM power spectrum is found to be generically suppressed in these cases as compared to the ΛCDM model. The degree of suppression at different length scales can, in principle, reflect the evolving nature of the ESS of dark energy. However, we find that the effect on the CDM power spectrum in cases where the ESS of dark energy is evolving with constant EOS parameter is significantly smaller as compared to the situation where ESS is constant whereas EOS parameter is evolving. Further, it is also shown that the effect of different evolution of ESS for a given evolution of EOS parameter of dark energy on the CDM power spectrum is significant only at the intermediate scales (around k ∼ 0.01h/Mpc). At scales much smaller and larger than the Hubble radius, it is the evolution of EOS parameter of dark energy which governs the degree of suppression of CDM power spectrum with respect to the ΛCDM model.