UCL Astrophysics Group


PhD Projects: Cosmology and Surveys

Understanding cosmology and galaxy evolution through intrinsic alignments

Galaxies are not randomly oriented in the sky but align with each other and their dark matter environment through poorly understood processes during the galaxies' formation and evolution. These intrinsic alignments thus provide a unique window on the interaction between galactic physics and the surrounding cosmic large-scale structure. Moreover, they severely limit the cosmological interpretation of weak gravitational lensing as well as galaxy clustering signals, the primary probes of major cosmological experiments in the 2020s. This project will build on our access to a unique combination of leading galaxy surveys, including the recently launched ESA Euclid mission, DESI - the largest spectroscopic galaxy survey ever undertaken, and the ESO KiDS and 4MOST experiments. The student will lead new alignment measurements in combinations of these datasets and model the signals both analytically and through cosmological simulations. Their work will directly feed into the interpretation of key cosmological measurements, e.g. with Euclid.

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

Cosmology from the Euclid space mission

 The ESA Euclid mission launched in July 2023 and has started to carry out the most detailed deep-Universe galaxy survey from Space ever made. Exciting new constraints on cosmological structure formation, dark matter and dark energy will be derived from the clustering of galaxies and general relativistic gravitational lensing effects. The student will join the Euclid Consortium and the Euclid team in the UCL Astrophysics Group to make key contributions to the measurement of cosmological signals and the modelling of cosmological, astrophysical, and observational signatures, both analytically and simulation-based.

Contact: Prof Benjamin Joachimi (b.joachimi 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.