Cosmic voids are emptier in the presence of symmetron's domain walls

TL;DR

This paper explores how symmetron domain walls influence cosmic voids, making them emptier and larger, which could help explain observed void phenomena in the universe.

Contribution

It introduces the impact of symmetron domain walls on cosmic voids, showing they cause voids to expand and become emptier, a novel effect in modified gravity models.

Findings

Void sizes increase due to repulsive forces from domain walls.

Voids become emptier compared to standard cosmology.

Potential explanation for Peebles' void phenomenon.

Abstract

The symmetron field has an environment (density) dependent behavior which is a common feature of the models with the screening mechanism and results in a rich phenomenology. This model can produce domain walls between regions with different densities. We consider this aspect and study the physics of domain walls in between (underdensity) voids and (overdensity) halo structures. The (spherical) domain walls exert a repulsive force on a test mass outside of the wall while a test mass inside of the wall sees no force. This makes the structures outside the voids go further to a larger radius. Effectively, this means the voids are becoming larger in this scenario in comparison to the standard model of cosmology. Interestingly, this makes voids emptier which may shed light on Peebles' void phenomenon.