Probing Cosmology with 92 Localized Fast Radio Bursts and DESI BAO

TL;DR

This work probes whether dynamical dark energy is favored by jointly analyzing 92 localized FRBs with DESI BAO, PantheonPlus, and Planck CMB data under the CPL EoS, $w(a)=w_0+w_a(1-a)$. It ties FRB dispersion measures to the expansion history via $H(z)$ and includes detailed modeling of DM contributions from the Milky Way, halo, and host galaxies, using MW electron-density models NE2001 and YMW16 and a physics-based halo model. The results show that without CMB data, dynamical dark energy is preferred with $w_0=-0.855^{+0.084}_{-0.084}$ and $w_a=-1.174^{+0.462}_{-0.491}$ (≈2.5σ), and a joint analysis with CMB yields $w_0=-0.784^{+0.064}_{-0.064}$ and $w_a=-0.872^{+0.269}_{-0.278}$ (≈3.1σ from ΛCDM). FRB-only inferences give $H_0=69.04^{+2.30}_{-2.07}$ or $75.61^{+2.23}_{-2.07}$ km s$^{-1}$ Mpc$^{-1}$ depending on the MW electron model, underscoring that accurate Galactic DM treatment is crucial for addressing the Hubble tension with FRBs. Future BAO, CMB, and more localized FRBs promise tighter constraints on the DE EoS and cosmological parameters.

Abstract

Recent baryon acoustic oscillation (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI) collaboration, combined with the cosmic microwave background (CMB) and type Ia supernovae (SNe Ia) observations, suggest a preference for dynamical dark energy (DDE) with $w_0>-1$ and $w_a<0$. Given the cosmological origin of fast radio bursts (FRBs), the combination of their dispersion measures and host galaxy redshifts makes localized FRBs a valuable tool for probing cosmology. Using an updated sample of 92 localized FRBs, along with DESI BAO, PlantheonPlus and CMB data, we constrain the dark energy (DE) equation of state (EoS) under the Chevallier-Polarski-Linder (CPL) parameterization. We find that even without incorporating CMB data, DDE remains preferred with $w_0 = -0.855 ^{+0.084}_{-0.084}$ and $w_a = -1.174^{+0.462}_{-0.491}$ at a confidence level of $\sim2.5 σ$. A joint analysis constrains these to be $w_0 = -0.784^{+0.064}_{-0.064}$ and $w_a = -0.872^{+0.269}_{-0.278}$, showing a discrepancy with $Λ$CDM at a $\sim3.1σ$ level. Furthermore, using localized FRBs alone, we estimate the Hubble constant $H_0$ to be $69.04^{+2.30}_{-2.07}$ and $75.61^{+2.23}_{-2.07} \, \rm km \, s^{-1} \, Mpc^{-1}$, assuming the Galactic electron density models to be NE2001 (Cordes \& Lazio) and YMW16 (Yao et al.), respectively. Thus, accurate accounting of the Galactic dispersion measure is crucial for resolving the Hubble tension with FRBs. Future BAO measurements, next-generation CMB experiments, and more localized FRBs will further constrain the DE EoS and the cosmological parameters.