Connecting galaxies to the cosmic web

This project will work on current and future galaxy redshift surveys BOSS / eBOSS / DESI which provide spectroscopic redshifts for an unprecedented volume of the Universe up to a redshift of 1. These surveys are incredibly powerful tools for cosmology in terms of improving constraints on dark energy and measuring the expansion history of the universe, but also have the potential for being useful tools for studying galaxy evolution due to the large number of galaxy observations.

However, with the focus being firmly on cosmology, these surveys target galaxies to maximise the volume surveyed. This results in incomplete samples (with respect to, e.g., a magnitude limited survey) with complex selection functions. The use of such surveys for galaxy evolution studies would be significantly improved if such a completeness could be estimated. If populations of galaxies with photometric and spectroscopic redshifts exist in the same region, then by cross correlating the two populations it is possible to recover the redshift distribution of the photometric sample. The initial goal of the project will be to use cross correlations to reconstruct the completeness of these surveys, re-instating them as versatile tools for galaxy evolution.

With this computed, more information can be obtained about the galaxy populations. This project will focus on modelling how galaxies in these surveys populate dark matter halos and how one can identify progenitors across redshifts and surveys. The results will allow better cosmological constraints as well as revealing the mass assembly in massive galaxies over the last 7 billion years of cosmic history.