Robust Evidence for Dynamical Dark Energy from DESI Galaxy-CMB Lensing Cross-Correlation and Geometric Probes

TL;DR

This paper provides strong, independent observational evidence for dynamical dark energy using Galaxy-CMB lensing cross-correlation combined with geometric probes, surpassing 4 sigma significance and reinforcing the case against a simple cosmological constant.

Contribution

It introduces new constraints on dynamical dark energy through Galaxy-CMB lensing cross-correlation, demonstrating its robustness and complementarity with geometric measurements.

Findings

Cross-correlation yields over 4 sigma evidence for DDE.

Results are independent of primary Planck CMB data.

Combining probes enhances robustness of dark energy constraints.

Abstract

Recent analyses joining data from the Cosmic Microwave Background (CMB), Baryon Acoustic Oscillations (BAO), and Type Ia Supernovae (SNIa) have provided strong evidence in favor of dynamical dark energy (DDE) over a simple cosmological constant. Motivated by these findings, we present new observational constraints on DDE based on the cross-correlation between DESI Luminous Red Galaxies (LRG) samples and CMB lensing ($\mathrm{CMB}_{\kappa} \times \mathrm{LRG}$), which effectively probes the impact of cosmological parameters on the growth of structure at the perturbative level. We demonstrate that, when combined with geometric measurements such as BAO and SNIa, this cross-correlation yields compelling statistical evidence for DDE exceeding $4\sigma$, including within simpler parametrizations such as the $w$CDM model. Remarkably, this evidence is independent of constraints from primary Planck CMB anisotropies data. These results highlight the robustness and potential of Galaxy-CMB lensing cross-correlation as a powerful observational probe of the dark sector, particularly when used in conjunction with geometric observables.