Title:

From agnostic to believer: theoretical conditions on phenomenological parametrizations

Abstract:

Recent low redshift observations highlights tensions in the measurements of cosmological parameters with CMB surveys. Although it is not ruled out that such tensions are due to some unforeseen systematic effect, it can also hint for a breakdown of the standard LCDM model.
This talk will introduce extensions or modifications of the standard cosmological model using phenomenological parametrizations, highlighting how these can reconcile low and high redshift observations.
Furthermore, it will describe the impact of theoretical priors on these parametrized approaches, focusing on agnostic studies of large scale structure observables, in the realm of scalar-tensor modifications of gravity.
The final goal is to establish a link between viable physical theories and such phenomenological departures from the standard cosmological model.