Cosmographic constraints from late-time probes including fast radio bursts

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 $\Lambda$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 $\Lambda$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 $1\sigma$ 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.