Tension on the Hubble constant: systematic uncertainties or new physics?

One of the most striking tensions that we have nowadays concerns the value of the expansion rate of the Universe today, the Hubble constant, which is close to a 5-sigma tension between the measurements derived from the cosmic microwave background and local measurements.

There are essentially two different reasons that could explain this tension. Either there are some unaccounted systematic uncertainties on the measurements, or there are new physics on our cosmological model that can change the value derived from high-redshift observations. In recent literature, there are plenty of articles focusing on one of these two options to solve the Hubble constant tension. In this talk, I will first give a brief introduction to some of the methods to estimate the value of the Hubble constant.

I will then present the results of a recent paper where we try to solve the tension by combining the addition of new physics and the addition of unaccounted systematic uncertainties on type-Ia supernovae data. And I will finish by presenting the most promising ideas that could finally solve the tension.