Continuous matter creation and the acceleration of the universe: the growth of density fluctuations

TL;DR

This paper explores cosmological models with continuous matter creation that mimic the standard Lambda-CDM model early on but diverge at late times, affecting structure formation and galaxy evolution.

Contribution

It introduces specific continuous matter creation models that replicate Lambda-CDM properties early but differ in late-time behavior, highlighting potential issues with structure formation.

Findings

Density fluctuation amplitude depends on creation rate parameter.

Models overestimate galaxy peculiar velocities.

Predicted cluster densities exceed observations.

Abstract

Cosmologies including continuous matter creation are able to reproduce the main properties of the standard $\Lambda$CDM model, in particular in cases where the particle and entropy production rates are equal. These specific models, characterized by a mass density equal to the critical value, behave like the standard $\Lambda$CDM model at early times whereas their late evolution is similar to the steady-state cosmology. The maximum amplitude of density fluctuations in these models depends on the adopted creation rate, related here to the parameter $\Omega_v$ and this limitation could be a difficulty for the formation of galaxies and large-scale structure in this class of universe. Additional problems are related with predictions either of the random peculiar velocities of galaxies or the present density of massive clusters of galaxies, both being largely overestimated with respect to observational data.