Cosmographic constraints from late-time probes including fast radio bursts

Context. Late-time astrophysical probes offer a powerful way to investigate the expansion history of the Universe. Among these probes, fast radio bursts (FRBs) are millisecond-duration astrophysical transients whose extragalactic origin makes them a promising addition for large-scale structure studies. Their dispersion measures encode information about the intervening cosmic plasma, which can be linked to cosmological distances. Aims. We used late-time probes, such as well-localized FRBs, baryon acoustic oscillations (BAOs), supernovae (SNe), and cosmic chronometers (CCs), to constrain cosmological parameters through a model-independent cosmographic approach. Methods. We integrated FRB data with BAOs from the Dark Energy Spectroscopic Instrument (DESI) DR2, SNe, and CCs to derive constraints on the Hubble constant ( H 0 ), the deceleration parameter ( q 0 ), and the jerk parameter ( j 0 ) using a Markov chain Monte Carlo (MCMC) analysis for parameter estimation. Results. The cosmographic approach with FRBs alone provides H 0 = 66.35 −5.04 +4.13 km s −1 Mpc −1 , q 0 = −0.33 −0.15 +0.21 , and j 0 = 0.83 −0.67 +0.57 , corresponding to a precision of ∼6% for H 0 and showing consistency with the lambda cold dark matter (ΛCDM) expectation. The BAO dataset from DESI DR2 yields H 0 = 65.59 −1.24 +1.25 km s −1 Mpc −1 , q 0 = −0.29 −0.08 +0.07 , and j 0 = 0.58 −0.04 +0.03 , providing a ∼2% precision on H 0 and may suggest a possible tension in the late-time kinematic sector relative to the ΛCDM expectation when BAO measurements are calibrated with a Planck-inferred sound horizon. Combining the FRB, SNe, DESI DR2, and CC datasets further tightens the constraints to H 0 = 68.03 −0.52 +0.53 km s −1 Mpc −1 , q 0 = −0.41 ± 0.02, and j 0 = 0.55 ± 0.02, with the jerk parameter remaining lower than j 0 = 1 at the 1 σ confidence level. Conclusions. 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 DR2 dataset under standard early-Universe assumptions for the sound horizon. At the current level of observational precision, FRBs play a complementary role in the cosmographic analysis, and their impact is expected to increase as larger, more precise samples of well-localized events become available.