Cosmographic constraints from late-time probes including fast radio bursts

TL;DR

This work develops a model-independent cosmographic analysis of the late-time expansion by combining FRBs with BAO, SNe, and CC to estimate $H_0$, $q_0$, and $j_0$ via Bayesian inference. FRBs alone yield a broad $H_0$ constraint around 66 km s$^{-1}$ Mpc$^{-1}$, while DESI+CMB delivers a sharp $H_0$ near 66 km s$^{-1}$ Mpc$^{-1}$ with $j_0$ tightly constrained; the joint FRB+SNe+DESI+CMB+CC analysis produces the most precise results, $H_0=68.03^{+0.53}_{-0.52}$, $q_0=-0.41 ightarrow-0.02$, and $j_0=0.55 ightarrow ext{−}0.02$, with $j_0<1$ at 1σ. The findings indicate a possible late-time kinematic tension, predominantly driven by DESI+CMB under pre-recombination assumptions for the sound horizon, and show FRBs as a valuable, complementary probe whose impact will grow with larger, more precise samples. Overall, the study demonstrates the power of cosmography as a monitoring tool for late-time expansion and provides independent cross-checks against standard ΛCDM inferences.

Abstract

In this study, we use late-time probes, such as well-localized fast radio bursts (FRBs), baryon acoustic oscillations (BAO), supernovae (SNe), and cosmic chronometers (CC) to constrain cosmological parameters through a model-independent cosmographic approach. By integrating FRB data with BAO from DESI DR2, SNe, and CC, we derive constraints on the Hubble constant ($H_0$), the deceleration parameter ($q_0$), and the jerk parameter ($j_0$), using Markov Chain Monte Carlo (MCMC) analysis for parameter estimation. The cosmographic approach with FRBs alone provides $H_0 = 66.35^{+4.13}_{-5.04} \, \text{km} \, \text{s}^{-1} \, \text{Mpc}^{-1}$, $q_0 = -0.33^{+0.21}_{-0.15}$, and $j_0 = 0.83^{+0.57}_{-0.67}$, corresponding to a precision of $\sim 6\%$ for the Hubble constant and showing consistency with the $Λ$CDM expectation. The DESI+CMB dataset yields $H_0 = 65.59^{+1.25}_{-1.24} \, \text{km} \, \text{s}^{-1} \, \text{Mpc}^{-1}$, $q_0 = -0.29^{+0.07}_{-0.08}$, and $j_0 = 0.58^{+0.03}_{-0.04}$, providing a $\sim 2\%$ precision on $H_0$ and may suggest a possible tension in the late-time kinematic sector relative to the $Λ$CDM expectation when BAO measurements are calibrated with a Planck-inferred sound horizon. Combining the FRB, SNe, DESI+CMB, and CC datasets further tightens the constraints to $H_0 = 68.03^{+0.53}_{-0.52} \, \text{km} \, \text{s}^{-1} \, \text{Mpc}^{-1}$, $q_0 = -0.41 \pm 0.02$, and $j_0 = 0.55 \pm 0.02$, with the jerk parameter remaining lower than $j_0 = 1$ at the $1σ$ confidence level. These findings hint at a possible late-time kinematic tension, as indicated by the inferred value of the jerk parameter, which is primarily driven by the DESI+CMB dataset under standard early-Universe assumptions for the sound horizon.

Figures (7)

• Figure 1: Two-dimensional marginalized contours for the localized FRB sample with $68.3\%$ and $95.4\%$ confidence levels for cosmography. These findings were obtained considering a flat prior for $\Omega_bh^2$ and a fixed value for $f_{\rm IGM}$.
• Figure 2: Corner plot exhibiting the marginalized 1D and 2D posterior distributions for the cosmological parameters $H_0$, $q_0$, and $j_0$, and the comparison of several datasets, including the result presented in Fig. \ref{['fig:4']}, and a joint analysis.
• Figure 3: Two-dimensional marginalized contours for the cosmographic parameters. From left to right, the plots depict the confidence regions in the $H_0-j_0$ and $H_0-q_0$ planes, respectively.
• Figure 4: The left (right) panel shows the normalized posterior probability distributions for the jerk (deceleration) parameter.
• Figure 5: Two-dimensional marginalized contours for the $q_0-j_0$ plane.