The main research focus areas of the extragalactic group at UCT are on galaxy evolution and star formation in different environments (from groups to clusters to large scale structure) and over cosmic time, as well as large scale structure and cosmic flows. Our group has a particular interest in HI galaxy science and has very broad participation in HI surveys on SKA pathfinder instruments including MeerKAT, JVLA, uGMRT and ASKAP. Three of the MeerKAT Large Survey Projects (LADUMA, MHONGOOSE, MIGHTEE) as well as the MIGHTEE-HI project, are co-led by members of the group.
Environmental influences on galaxy evolution
The environment in which a galaxy is located can have a significant impact on its evolution. Our group studies the physical processes taking place in different environments using a multi-wavelength approach involving spectroscopy, multi-band photometry and HI 21cm emission.
Star formation in galaxies, how the gas necessary to support it is acquired, and how it evolves over cosmic time
The star formation history (SFH) is one of the key observables to understand the evolution of galaxies and key ingredients of semi-analytic and cosmological simulations trying to reproduce the formation and evolution of galaxies. The answers to these questions can be probed by using radio continuum data (e.g. from MIGHTEE) to measure star formation as well as deep HI observations (e.g. MHONGOOSE) to probe the neutral gas in and around the outskirts of galaxies. How the gas content of galaxies evolves over cosmic time will be measured using deep HI observations spanning a range of redshifts (LADUMA).
Active galactic nuclei and radio galaxies in the context of galaxy evolution
There are several outstanding questions related to AGN and galaxy evolution including: What can giant radio galaxies teach us about radio-mode feedback and the AGN duty cycle? What is the extent of star formation inside AGN host galaxies during different phases of activity? How is this related to the HI gas content and feedback mechanisms? What is the connection between the fuelling and final point of star formation? Our group is investigating these questions using multiwavelength data including optical spectroscopy, multi-wavelength photometry as well as radio continuum and HI observations.
Large scale structure and cosmic flows
The large-scale structure of the universe takes the form of a so-called cosmic web where the nodes consist of the high density regions of galaxy clusters and superclusters connected by filaments surrounding much lower density regions called voids. Large mass overdensities like superclusters cause cosmic flows due to their large gravitational influence. Our group is interested in mapping the extragalactic large-scale structures hidden by the Milky Way using spectroscopy, the 21-cm line emission of neutral hydrogen as well as infrared photometry.
Cosmic magnetism
Magnetic fields are known to be ubiquitous in the universe, and understood to play a strong role in astrophysical processes. However the origins of magnetism in the cosmos and the evolution of magnetic fields and their relation to the evolution of large-scale structure and the physical evolution of matter in the universe are not known. These questions form one of the five key science drivers of the Square Kilometre Array project.
Staff members involved in this research area:
A/Prof. Sarah Blyth
Dr Jacinta Delhaize
Dr Lucia Marchetti
Dr Moses Mogotsi
Prof. D.J. Pisano
Prof. Erwin de Blok
Dr Bradley Frank
Em. Prof. Renee Kraan-Korteweg
Dr Rosalind Skelton
Prof. Mattia Vaccari
Em. Prof. Russ Taylor