# Constraints on the dark energy dipole from large-scale structures

## TL;DR

This paper uses large-scale structure signals, specifically the X-SZ cross-correlation, to test the isotropy of the Universe and constrain the dark energy dipole, achieving tight limits on anisotropy.

## Contribution

It introduces a localized measurement of the X-SZ cross-correlation to constrain cosmological parameter isotropy and the dark energy dipole.

## Key findings

- Derived cosmological constraints: σ₈(Ωₘ/0.28)^0.34 = 0.78 ± 0.02
- Tight isotropy constraint on dark energy dipole: ΔΩ_Λ < 0.07 at 95% CL
- Confirmed the isotropy of large-scale structure signals across the sky.

## Abstract

The high-significance measurement of large-scale structure signals enables testing the isotropy of the Universe. The measurement of cosmological parameters through the large-scale distribution of matter is now a mature domain. This approach is mainly limited by our knowledge of astrophysical processes that are used to observe the large-scale structure. However, when we assume that these astrophysical processes are the same across the Universe, then it is possible to tightly constrain the isotropy of cosmological parameters across the sky. Particularly the X-SZ cross-correlation has been shown to be a probe of the large scale structures that has a high signal-to-noise ratio and low bias. For this analysis, we used a localized measurement of the X-SZ cross-correlation as a test of the cosmological parameter isotropy. Using the scatter of the X-SZ cross-correlation across the sky, we derive cosmological constraints $\sigma_{8} \left( \Omega_{\rm m}/0.28 \right)^{0.34} = 0.78 \pm 0.02$ and tight isotropy constraints on the dark energy dipole $\Delta \Omega_{\Lambda} < 0.07$ at 95\% confidence level.