Probing Cosmic Curvature with Fast Radio Bursts and DESI DR2

TL;DR

This study demonstrates that Fast Radio Bursts, combined with DESI DR2 data, can be used as a model-independent method to constrain the Universe's spatial curvature, showing consistency with flatness.

Contribution

It introduces a novel, cosmology-independent approach using FRBs and BAO data to measure cosmic curvature, highlighting the potential of FRBs in precision cosmology.

Findings

Constraints on $\

Both covariance and Gaussian methods yield results consistent with flatness.

FRBs can serve as a powerful, independent probe of the Universe's large-scale geometry.

Abstract

The spatial curvature of the Universe remains a central question in modern cosmology. In this work, we explore the potential of localized Fast Radio Bursts (FRBs) as a novel tool to constrain the cosmic curvature parameter $\Omega_k$ in a cosmological model-independent way. Using a sample of 120 FRBs with known redshifts and dispersion measures, we reconstruct the Hubble parameter $H(z)$ via artificial neural networks, and use it to obtain angular-diameter distances $D_A(z)$ through two complementary approaches. First, we derive the comoving distance $D_C(z)$ and $D_A(z)$ directly from FRBs without assuming a fiducial cosmology. Then, we combine the FRB-based $H(z)$ with Baryon Acoustic Oscillation (BAO) DESI DR2 measurements to infer $D_A(z)$. By comparing the FRB-derived and BAO+FRB-derived $D_A(z)$, we constrain spatial curvature. Our covariance-based likelihood (accounting for correlated uncertainties) yields $\Omega_k = -0.31\pm0.57$, while a diagonal (Gaussian) treatment gives $\Omega_k = -0.13\pm0.46$. Both estimations are consistent with spatial flatness at the $1\sigma$ level, albeit with a mild preference for negative curvature. Explicitly accounting for the full covariance broadens the intervals and avoids underestimation of uncertainties. These results highlight the growing relevance of FRBs in precision cosmology and their synergy with BAO as a powerful, cosmological model-independent probe of the large-scale geometry of the Universe.