Study of f(T) Mass Function of Nearby Galaxy Clusters: Determining σ8

This paper presents a new analytical method to determine amplitude of density fluctuations of 152 nearby clusters (z ≤ 0.15). We investigate the rms linear fluctuation in the mass distribution on scales of 8h−1M pc i.e. σ8 , by using Press-Shechter mass function. The mass function is estimated for masses larger than Mlim = 4 ×1014h−1M⊙. We find rms density fluctuation equal to 0.52 for the critical density universe. The results found are consistent with those, obtained with alternative models for the high density universe. The results agree with the previous papers obtained from different models and considerations. This takes us to introduce a new approach to estimate the cosmological parameters. For critical density , the slight variation in results may be due to the fact that there are observational uncertainties in estimates of cluster masses, which are in general not neglegible.