Jon Loveday


Galaxy surveys with 4MOST, Euclid and LSST

This project will ensure that we are well-prepared to fully exploit data from upcoming galaxy surveys, in particular the 4-metre Multi-Object Spectrograph (4MOST, Cosmology and WAVES surveys, but also imaging data from Euclid ( and LSST (  These surveys will revolutionise our understanding of galaxy evolution and cosmology.  Studying the small-scale clustering and dynamics of galaxies, typically in group environments, will be used to constrain the nature of dark matter.

 Specific sub-projects include, but are not limited to:

1. Group identification.  Various methods have been proposed for identifying groups of galaxies in spectroscopic surveys, such as friends-of-friends, halo-based, and probabilistic methods.  Using current survey and simulated data, you will explore the pros and cons of the various methods in order to identify an optimum group catalogue in 4MOST survey data.

2. 4MOST selection functions.  Not every target galaxy will have a successfully measured redshift: some will be missed due to observing constraints, others will be observed, but may lack features that allow redshift determination.  Keeping track of survey completeness will be vital for accurate determination of galaxy clustering.  You will use realistic simulations to test proposed methods for tracking survey completeness.

3. Use of marked correlation functions to distinguish cosmological models.  Weighting, or 'marking' each galaxy by a measure of its environment generalises the clustering of void galaxies at one extreme, and clusters at the other.  You will use state of the art simulations to optimise weighting schemes to gain maximum cosmological information.

4. Low surface-brightness galaxies.  Current determinations of the abundance of dwarf galaxies are almost certainly underestimates due to incompleteness in low-surface brightness galaxies in extant imaging surveys such as SDSS.  Euclid and LSST will enable detection of galaxies of much lower surface brightness than hitherto possible over large areas of sky, allowing accurate estimates of the abundance of these faint objects.  This in turn will provide important constraints on the nature of dark matter.

 Funding: STFC quota studentship or other

 For more information/to apply for this project, please contact