Suppression of matter density growth at scales exceeding the cosmic screening length

TL;DR

This paper demonstrates that matter density contrasts do not grow over time at scales larger than the cosmic screening length due to a relativistic effect, confirmed through N-body simulations showing a scale-independent power spectrum.

Contribution

It introduces the concept of cosmic screening length as a scale beyond which density growth is suppressed, supported by relativistic analysis and large-scale N-body simulations.

Findings

Density contrasts do not grow at scales larger than the cosmic screening length.

The power spectrum becomes time-independent beyond this scale.

The effect is purely relativistic and manifests as an exponential cut-off.

Abstract

One of the main objectives of modern cosmology is to explain the origin and evolution of cosmic structures at different scales. The principal force responsible for the formation of such structures is gravity. In a general relativistic framework, we have shown that matter density contrasts do not grow over time at scales exceeding the cosmic screening length, which corresponds to a cosmological scale of the order of two to three gigaparsecs at the present time, at which gravitational interactions exhibit an exponential cut-off. This is a purely relativistic effect. To demonstrate the suppression of density growth, we have performed N-body simulations in a box with a comoving size of $5.632\,{\rm Gpc}/h$ and obtained the power spectrum of the mass density contrast. We have shown that it becomes independent of time for scales beyond the cosmic screening length as a clear manifestation of the cosmic screening effect.