The Effect of Cosmological Background Dynamics on the Spherical Collapse in MOND

TL;DR

This paper examines how different cosmological background dynamics influence the spherical collapse process in MOND, revealing that dark energy slows structure formation and affects virialization timing and size.

Contribution

It introduces a spherical collapse model in MOND considering two extreme background cases, highlighting the impact of dark energy on structure formation.

Findings

Structures virialize at lower redshifts with larger radii in dark energy dominated universe.

Dark energy slows down the collapse process in MOND.

Results align with recent MOND structure formation simulations.

Abstract

The effect of background dynamics of the universe on formation of large scale structures in the framework of Modified Newtonian Dynamics (MOND) is investigated. A spherical collapse model is used for modeling the formation of the structures. This study is done in two extreme cases: ({\it i}) assuming a universe with a low-density baryonic matter without any cold dark matter and dark energy; ({\it ii}) a dark energy dominated universe with baryonic matter, without cold dark matter. We show that for the case ({\it ii}) the structures virialize at lower redshifts with larger radii compared to the low-density background universe. The dark energy slow downs the collapse of the structures. We show that our results are compatible with recent simulations of the structure formation in MOND.