Institution(s): 1. Gauhati University Observatory
The bound on the cosmological constant energy density produced by big bang nucleosynthesis,0.786≤ΩΛ≤0.844 has been used to study the growth rate of large scale structure. The equation of state of dark energy is found to vary with a rate, △ω/△t≈10-14yr-1 since the time of decoupling and it levels off at about ω≈-0.996 for all the values of ΩΛ permitted by nucleosynthesis. This equation of state along with spectral index, n≈0.9 permitted by WMAP data yields growth rate which saturates at about z≈0.4 . The growth is suppressed below z≈0.4 . Observed growth data satisfies the trend of evolution. It strengthens the case for ΛCDM with nucleosynthesis bound on dark energy consistent with structure formation. The minute departure from scale invariance in presence of dark energy generates a mass scale M18=434.53-817.71 and a length scale λpeak=935.02-1283.94 Mpc. This elevation of structure mass and length may be a new feature of the ΛCDM model. The results may call for a serious look into the nature of dark energy and gravity itself.