Cosmology Beyond Homogeneity and Isotropy

ended

I will carry out a research program to understand how cosmological structures evolve and how the corresponding observables are modified in an inhomogeneous universe. This project will place the field of inhomogeneous cosmologies into the era of precision cosmology. Indeed, it is very difficult to obtain the evolution of structures when the background is inhomogeneous and it has not been possible to fully constrain inhomogeneous cosmologies because of this lack of understanding. As I will argue, the most promising approach is via Numerical Cosmology. This justifies why this fellowship will be carried out at the Astronomical Observatory of Trieste under the supervision of Stefano Borgani, one of the world experts in Numerical Cosmology. The scientific motivation behind this effort is that cosmology is undergoing a crisis, facing, at the same time, unexplained components (dark matter and dark energy) and a >4sigma tension between local and global determinations of the Hubble constant. It is then imperative to test basic assumptions in cosmology, such as large-scale homogeneity and isotropy. These are indeed among the objectives of many major space- and earth-based international collaborations (Euclid, LSST, SKA), which will produce detailed maps of a good fraction of the observable universe. Only after carrying out these tests can one hope to discover the nature of dark matter and dark energy.