GALAXY-HALO CONNECTION AND CLUSTERING IN THE PRESENCE OF DYNAMICAL DARK ENERGY AND MASSIVE NEUTRINOS

This work is focussed on the modelling of the connection between dark matter subhaloes and galaxies, and the analysis of the galaxy cluster mass function and clustering, in cosmologies alternative to the standard LCDM model. To this aim a large set of cosmological N-body simulations has been used, the so-called “Dark Energy and Massive Neutrino Universe” (DEMNUni) project, spanning several cosmological models with different neutrino masses and/or different equations of state of dynamical dark energy. The author of this Thesis has applied to these simulations the subhalo abundance matching (SHAM) technique, which assumes a one-to-one relation between a physical property of a dark matter halo/subhalo and an observational property of the galaxy that it hosts. The author has adopted an empirical parameterisation of the stellar-to-halo-mass relation (SHMR) from Moster et al. (2010) that links the halo mass to the corresponding stellar mass of a galaxy hosted by the halo. Via a MCMC bayesian approach, the author has computed the best-fit parameters of the SHMR as a function of redshift in the presence of dark energy and massive neutrinos, considering the datasets from the Sloan Digital Sky Survey (SDSS) for redshifts z < 0.2, and from the Cosmological Evolution Survey (COSMOS 2020) for 0.2 < z < 2. Implementing such a method, the author has populated with galaxies the dark matter structures in the DEMNUni simulations finding the dependence of the SHMR on the total neutrino mass and the dark energy equation of state. The obtained galaxy mocks account both for central and satellite galaxies, spanning the redshift range 0 < z < 2, which covers both the photometric and spectroscopic galaxy samples of the upcoming Euclid survey. Finally, the author has estimated the galaxy and galaxy-cluster properties from the simulated galaxy and galaxy-cluster catalogues extracted from the DEMNUni simulations, such as the halo-mass-function, the matter/halo/galaxy power spectra, the correlation function both in real and redshift space and the multipoles of the power spectrum in redshift space. Also, from these measurements she has measured the bias of the produced mock galaxy and galaxy cluster catalogues and estimated how it changes in different massive neutrinos and dynamical dark energy scenarios.