Galaxy-halo connection in cosmology with wide spectroscopic surveys —

Since the early 2000s, wide spectroscopic surveys, in particular multi-fibre experiments, have provided significant insights into the three-dimensional distribution of galaxies and quasars in the Universe, by constraining cosmological parameters through precise measurements of the baryon acoustic oscillation (BAO) scale and the non-linear growth rate of structure from redshift space distortions. Current and upcoming stage IV spectroscopic surveys, such as the Dark Energy Spectroscopic Instrument (DESI) or the 4-metre Multi-Object Spectrograph Telescope (4MOST) aims to reach sub-percent precision on cosmological parameters over a broad redshift range of 0.1 < z < 3.5.
In this talk, I will give an overview of the DESI survey and its scientific goals. In particular, I will focus on the galaxy-halo connection, i.e. how galaxies are connected to the underlying matter field. I will present results obtained using the early data release of DESI to constrain the connection between DESI galaxies (luminous red galaxies (LRGs) and Emission Line Galaxies (ELGs)) using the halo occupation distribution (HOD) framework, an empirical approach to link galaxies and dark matter halos in N-body simulations.