Topological defects as effective dynamical dark energy

TL;DR

This paper explores whether topological defects like domain walls and cosmic strings can mimic dynamical dark energy effects, finding that domain walls slightly improve model fits while cosmic strings do not show preference.

Contribution

It introduces the idea that topological defects could serve as an alternative explanation for dynamical dark energy signals in cosmological data.

Findings

Domain walls at percent level improve fit to data

Cosmic strings show no preference in data

Topological defects remain a viable extension to ΛCDM

Abstract

In this work, we consider the possibility that the dynamical dark energy hinted at by recent DESI data may be mimicked by the effects of additional components in the universe, potentially arising from topological defects. We find that the data does not show a particular preference for the existence of cosmic strings. However, a domain wall contribution at the percent level can improve the fit, yielding a $\Delta \chi^2= -1.72$ compared to the $\Lambda \rm{CDM}$ model. The improvement indicates that topological defects remain a viable and interesting extension to $\Lambda\rm{CDM}$, meriting further investigation with future cosmological data.