My research explores the evolution of galaxies over the last 11 billion years (since z~3), incorporating a number of different projects on galaxy interactions, the growth and quenching of galaxies and environmental effects on galaxies in dense clusters and groups.

I am working with MSc student Nazir Makda (National Astrophysics and Space Science Programme, UCT) and Sarah Blyth (UCT) on ultra diffuse galaxies (UDGs) in Stripe 82 clusters.  Jamie Bok (PhD student, UCT) is working on Alfalfa observations of galaxies in pairs, together with Tom Jarrett (UCT) and Michelle Cluver (IDIA, UWC).

At the SAAO, I work with David Gilbank on a project that uses SALT and large public surveys like the Sloan Digital Sky Survey (SDSS) to pin down the fraction of luminous red galaxies (LRGs) in close pairs . A related project, led by Danièl Groenewald, is exploring the growth history of Brightest Cluster Galaxies (BCGs), the most massive galaxies in dense environments. We are also using the wide field of the KMTNet telescope to study faint, low surface brightness structures around nearby galaxies, groups and clusters.

I am part of the Hubble Frontier Fields DeepSpace collaboration that is combining the excellent quality HST data on the six Frontier Fields clusters and parallel fields into photometric catalogues (PI: Danilo Marchesini). In just one of the projects making use of this data, we are exploring the incidence of galaxy interactions in intermediate redshift clusters (Honours student project, Munira Hoosain, UCT).

I am involved in the 3D-HST project, led by Pieter van Dokkum at Yale University, which uses the WFC3 camera on the Hubble Space Telescope to determine the distances and properties of thousands of high redshift galaxies. I led the effort to combine the wealth of data covering the 3D-HST/CANDELS fields into comprehensive multiwavelength photometric catalogues (Skelton et al. 2014). These catalogues are vital for the reduction of the low-resolution slitless spectroscopic data from the WFC3 grism, which allow us to pin down galaxy redshifts to within 1000 km/s. The HST resolution and excellent redshifts enable us to identify galaxies in close pairs that are likely to merge with each other and study their properties in detail.


Most recent publication:

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3D-HST Catalogue paper and Data Release v4.1:

The catalogues are described in depth in Skelton et al. 2014. See the 3D-HST webpage for more details and to download the catalogues and images used in the analysis. This is the culmination of 3 years of hard work! Many thanks to the team, especially to Iva Momcheva, who put together the release, Kate Whitaker, who worked on the catalogues with me, Pieter van Dokkum and Gabe Brammer.