2023MNRAS.526.1773F

Fast radio bursts (FRBs) are millisecond-duration pulses occurring at cosmological distances that have emerged as prominent cosmological probes due to their dispersion measure (DM) evolution with redshift. In this work, we use cosmography, a model-independent approach to describe the evolution of the Universe, to introduce the cosmographic expansion of the DM- z relation. By fitting two different models for the intergalactic medium and host contributions to a sample of 23 well-localized FRBs, we estimate the kinematic parameters $q_0=-0.59^{+0.20}_{-0.17}$, $j_0=1.08^{+0.62}_{-0.56}$, s₀ = -2.1 ± 7.0, and H₀ = 69.4 ± 4.7 achieving a precision of 6 per cent and 7 per cent for the Hubble constant depending on the models used for contributions. Furthermore, we demonstrate that this approach can be used as an alternative and complementary cosmological model-independent method to revisit the long-standing 'Missing Baryons' problem in astrophysics by estimating that 82 per cent of the baryonic content of the Universe resides in the intergalactic medium, within 7 per cent and 8 per cent precision, according to the contribution models considered here. Our findings highlight the potential of FRBs as a valuable tool in cosmological research and underscore the importance of ongoing efforts to improve our understanding of these enigmatic events.