### Conveners

#### Parallel Session 1 (Cosmology I)

- Session convener: Mar Bastero-Gil

We introduce new parameterisations of dark-energy which continuously deform the special $\Lambda$CDM model. In addition, we provide the functional form of the parameters when dark-energy is described by thawing and tracking quintessence models.

Cosmological models that incorporate an elastic interaction within the dark sector at the linear order have emerged as a promising solution to address the σ8 tension. This interaction works by preventing the clustering of dark matter, thereby alleviating the tension. A key question in these scenarios is whether there is a potential degeneracy between this dark sector interaction and the impact...

The perturbation theory of the Friedmann-Lemaître-Robertson-Walker models seems to provide a good explanation of the observed degree of inhomogeneity in the universe, but the structure and evolution of galaxies, clusters, and voids require an analysis outside of the perturbative regime. They are often modeled by Newtonian N-body computations. However, the non-linear effects of the Einstein...

A family of relativistic models of thin disks and spheroidal haloes with magnetically polarized material source it is presented. The models are built using exact solutions of the Einstein-Maxwell equations for a conformastatic and axially symmetric spacetime, by assuming that the material content of the halo is described by a non-dissipative anisotropic fluid and that the magnetic polarization...