Cosmographic constraints from FRBs

The cosmographic approach with FRBs alone provides H0=66.35^+4.13^_-5.04_km/s/Mpc, q0=-0.33_-0.15_^+0.21^, and j0=0.83_-0.67_^0.57^, corresponding to a precision of ~6% for the Hubble constant and showing consistency with the {LAMBDA}CDM expectation. The DESI+CMB dataset yields H0=65.59^+1.25^_-1.24_km/s/Mpc, q0=-0.29_-0.08_^+0.07^, and j0=0.58_-0.04_^+0.03^, providing a ~2% precision on H0 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 H0=68.03^+0.53^_-0.52_km/s/Mpc, q0=-0.41+/-0.02, and j0=0.55+/-0.02, with the jerk parameter remaining lower than j0=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.

At the current level of observational precision, FRBs play a complementary role in the cosmographic analysis, with their impact expected to increase as larger and more precise samples of well-localized events become available.