Although the $\Lambda$CDM model has been remarkably successful in explaining a wide range of observational data, the model does not reconcile distance-redshift measurements when anchored at low redshift through the distance ladder and high redshift by cosmic microwave background (CMB) anisotropies. Specifically, if we assume the $\Lambda$CDM model, the Hubble parameter $H_0$ has a $4.1\sigma$ tension between the measurements from low redshift SH0ES project and the high redshift Planck CMB data. This "Hubble tension" has become an increasingly significant mystery to solve in recent years. In this seminar, I will talk about the currently proposed solutions for the Hubble tension. Acoustic Dark Energy (an Early Dark Energy-like) model could provide the high H0 solution with simple scalar field realization, at the cost of a higher S8 value. On the other hand, early modified gravity could provide a different mechanism to relieve Hubble tension with a low S8 value.
The possible paths to better solutions in the future will also be talked about.
Meeting ID: 973 3662 1524