Cosmographic view on the H0 and σ8 tensions

Measurements of the H0 and u8 parameters within the standard cosmological model recently highlighted significant statistical tensions between the cosmic microwave background and low-redshift probes, such as local distance ladder, weak lensing, and galaxy clustering surveys. In this work, we frame geometrical distances in a model-independent way by means of cosmographic approximations in the range z is an element of (0; 2.3) to take into account a robust dataset composed of baryon acoustic oscillations (BAOs), type Ia supernovae (SN), cosmic chronometer (CC) data, and measurements from redshift space distortions (RSDs). From the joint analysis BAO + SN + CC + RSD, we find an accuracy of similar to 1.4% and similar to 3.7% on H0 and u8, respectively. Our result for H0 is at 2u tension with local measurements by the SH0ES team, while our u8 estimate is at 2.6u tension with Planck-CMB analysis. This inference shows a tension statistically smaller when compared to those estimated via the Lambda cold dark matter (ACDM) model. We also find that the jerk parameter can deviate more than 3u from the ACDM prediction. Under the same cosmographic setup, we also present results by considering a SH0ES Gaussian prior on H0 that allows for improved accuracy of the parameter space of the models. The present work brings observational constraints on H0 and u8 into a new modelindependent perspective, which differs from the predictions obtained within the ACDM paradigm.