Evidence for departure from \Lambda CDM with LSS

TL;DR

This study analyzes large scale structure data to test the mbda CDM model and finds significant deviations, suggesting Einstein's General Relativity may be inconsistent with current observations at high confidence levels.

Contribution

It provides the first constraints on the growth index mma and effective gravitational constant G_{eff} using recent f(z) data, challenging the mbda CDM model.

Findings

mbda CDM model is excluded at 1-mbda level from current data.

G_{eff} differs from G_{N} at z .2-0.3 at 3-mbda level.

General Relativity with mbda CDM is ruled out at 99% confidence level.

Abstract

We investigate the growth index parameter \gamma and the time variation of the gravitational constant G_{eff} by using the currently available growth function f(z) data at different redshifts, with and without scaling to the fiducial \Lambda CDM model. We inquire the four different models of \gamma including a constant \gamma. From a \chi^2 minimization, we constrain the parameter spaces of models and show that \Lambda CDM model is excluded by 1-\sigma level from current f(z) data. G_{eff} is different from the Newton's gravitational constant G_{N} in modified gravity theories and interestingly, the current data shows that G_{eff} \neq G_{N} at z \gtrsim 0.2 \sim 0.3 at 3-\sigma level. From these, we conclude that Einstein's General Relativity with \Lambda CDM is ruled out by 99% confidence level from large scale structure observations.