PhD Projects: Cosmology and Surveys

The DESI view of galaxies in their dark matter neighbourhood

DESI is already the largest spectroscopic redshift survey ever undertaken, and will complete observations of an extremely powerful spectroscopic dataset during the course of this PhD project. Moreover, DESI overlaps with large and deep imaging surveys from both Space (Euclid) and the ground (e.g., the LSST). The student will leverage the sky overlap of these surveys to characterise how the locations, masses, and shapes of galaxies relate to the dark matter distribution surrounding them. By comparing to large cosmological simulations as well as analytic models, we can gain insight into the formation history of galaxy types and also improve the modelling of cosmological signals.

Contact: Prof Benjamin Joachimi (b.joachimi AT ucl.ac.uk) 

Beyond the cosmological standard model with the Euclid space mission

The ESA Euclid mission launched in July 2023 and is now carrying out the most detailed deep-Universe galaxy survey from Space ever made. During the course of this PhD project, the Euclid Consortium will prepare the second of three data releases, with major contributions from UCL staff. This powerful dataset and combinations of several cosmological probes will allow us to constrain extensions of the cosmological standard model with astonishing precision. The student will take a leading role in determining new insights into models of dark energy and modifications to the laws of gravity.

More specifically, this project will involve both strong theoretical and data-driven components. On the theory side, the student will predict novel theoretical signatures and constraints, using cosmological perturbation theory as well as so-called effective field theory techniques. On the data-driven side, the student will test these signatures using Euclid data sets as well as data from complementary probes, e.g. involving the computation of cross correlations with cosmic microwave background measurements. Overall, this project will therefore use a wide spectrum of techniques to gain novel insights into the underlying physical nature of dark energy and the laws of gravity. 

Contact: Prof Benjamin Joachimi (b.joachimi AT ucl.ac.uk) and Dr Johannes Noller (j.noller AT ucl.ac.uk)

Mapping and Measuring the Universe with DESI

The PhD project will focus on extracting cosmological and astrophysical information from the Dark Energy Spectroscopic Instrument (DESI, https://www.desi.lbl.gov/), which will map the 3D distribution of about 35 million galaxies. The survey has already reached a milestone, measuring over 20 million galaxy and QSO spectra. This is perfect timing for a PhD project starting in October 2024. UCL has contributed to the instrumentation and science of DESI since its early days, and the PhD student will become a member of the international DESI collaboration, working with teams from around the world. The work will use statistical measures such as Minimum Spanning Tree to characterise the Cosmic Web in the galaxy distribution observed by DESI, beyond the 2-point statistics, and further AI approaches.
See an outreach video: "5000 eyes: mapping the universe with DESI"

Contact: Prof Ofer Lahav (o.lahav AT ucl.ac.uk)

Related projects are also advertised under Cosmoparticle Physics and Extragalactic Astrophysics.