Research Chairs

Five SKA SA Research Chairs allocated to South African Universities have been filled by leading international researchers.

The SA Research Chairs Initiative (SARChI) of the Department of Science and Technology and the National Research Foundation aims to strengthen science and engineering in SA by attracting and retaining excellence in research and innovation at South African universities.

Prof Oleg Smirnov – Rhodes University

1001“The development of radio astronomy calibration and imaging techniques has historically been punctuated by distinct generational shifts,” says Prof Smirnov. The discovery of the SelfCal algorithm in the 1980s ushered in the ‘second-generation calibration’ (2GC) era, and resulted in a rapid blossoming of software and methods. These were so successful and allowed so much new science to be done that the community’s focus shifted to the application of SelfCal, rather than development of new approaches. “Most radio astronomers spent the next two decades reaping the benefits of these applications, while only a small number of people worldwide kept specialising in the techniques themselves.”

But, the past ten years have seen a surge in the development of new radio telescopes, such as the SKA pathfinders, of which MeerKAT is a prime example. By virtue of their large scale and novel observational regimes, the capabilities of these instruments would be compromised by the old 2GC methods. With the SKA itself around the next corner, it has become increasingly clear that new methods need to be developed. This has fuelled demand for third-generation (3GC) techniques, and has provoked a very rapid development of the field.

These circumstances have created a situation in which a small number of specialists are trying to solve an overwhelming amount of interesting new problems. There is much new ground to explore, and not enough scientists to explore it. This provides an extremely fertile environment for young researchers and students, and offers an opportunity for Rhodes – and, more broadly, the South African radio astronomy community in general – to take the lead in the field.

Contact details: o.smirnov@ru.ac.za / +27 (0)46 603 7535

Prof David Davidson – Stellenbosch University

1002The Chair headed by Prof Davidson at Stellenbosch coordinates an extensive SKA-related research programme in the Department of Electrical and Electronic Engineering. This includes work by full-time academic staff and some twenty post-graduate students and post-doctoral students involved on the simulation and design of the antennas, radio frequency front-ends (feeds and receivers), correlators and electromagnetic interference studies, as well as work on characterising the overall interferometric array and high performance computing (HPC).

In terms of computational electromagnetics, the numerical solution of Maxwell’s equations using computers helps engineers refine receptor designs and create entirely new ones. For the SKA, they are focussing particularly on efficient simulation of focal plane arrays, a promising but challenging technology.

Designing the main reflecting dish and the feed is a demanding operation. Although the dish lasts for many years, feeds are continuously evolving to meet new science requirements, and take advantage of new technologies. Stellenbosch is actively involved in both fields, and has contributed extensively to the new offset Gregorian antenna design for MeerKAT.

Work is also done on the mitigation of radio frequency electromagnetic interference, which ensures that the very weak radio signals from the cosmos are not drowned out by either interference caused off-site, or by noisy electrical or electronic elements in the system itself.

In terms of the overall array characterisation, understanding a system as large as the SKA is important to guide work on individual components. Finally, work on HPC will contribute to both antenna and feed simulations, as well as in the data processing for the system. The team works in this field in collaboration with the National Centre for High Performance Computing and the University of Cape Town.

Contact details: davidson@sun.ac.za / +27 (0)21 808 4458

Prof Claude Carignan – University of Cape Town

1003The SKA Research Chair in Extragalactic Multi-Wavelength Astronomy is headed by Prof Claude Carignan. He says that after many years of experience using radio synthesis techniques with the Westerbork array in the Netherlands, the Very Large Array in the USA, the Australia Telescope Compact Array in Australia and the Dominion Radio Astronomical Observatory in Canada, the idea is to apply those techniques to study the most abundant gas in the Universe, neutral hydrogen (HI), using first the prototype KAT-7 (2012), thereafter the MeerKAT (2016) and finally the full SKA instrument (2025).

Multi-Wavelength astronomy means combining radio observations with data obtained at other wavelengths of the electromagnetic spectrum (UV, optical, infrared, X-rays and gamma-rays). For example, a large program has started making optical spectroscopy observations on the SALT telescope of the MHONGOOSE galaxy sample that will be observed in HI with MeerKAT. All those observations (radio and optical) will be combined to study the mass distribution in galaxies with the aim to answer two fundamental questions in astronomy: how much dark matter is there in galaxies, and how is it distributed. Once those two questions have been answered, we should be able to address the nature of dark matter, which does not emit any detectable radiation, but which we know is present by its gravitational influence on visible matter.

Contact details: ccarignan@ast.uct.ac.za /+27 (0)21 650 2395

Prof Roy Maartens – University of the Western Cape

1004“The SKA will be a wonderful instrument for cosmology” says Prof Maartens. It will reach deeper into space and further back in time than optical telescopes and provide the largest ever ‘moving map’ of the Universe. Maartens and the team of researchers working with him are developing the theoretical tools to interpret this moving map and to test our models of the Universe against the wealth of data in the map. This work involves a combination of physics theory, astronomy and statistics, and it relies on computers to deal with complex equations and huge amounts of data.

The sheer size of the SKA map of the Universe brings into play new effects from Einstein’s theory of general relativity. These new effects have only recently been discovered by cosmologists, and much work remains to be done to explore them. We need to understand the general relativity effects in order to use the SKA data as a probe of dark energy and other features of the Universe.

Different members of the team work on different aspects. The MSc, PhD students and postdoctoral researchers in the team share knowledge and help each other, and they interact with other researchers in the UWC Astrophysics Group (http://uwcastro.org). The UWC group, which was set up by Prof Catherine Cress in 2008 with support from the SA SKA project, includes experts on radio and optical astronomy, and on techniques for analysing observational data.

Contact details: rmaartens@uwc.ac.za / +27 (0)82 680 0294

Prof Sergio Colafrancesco – University of the Witwatersrand

1005The current main research strategy of Prof Colafrancesco is to use radio astronomical observations with the most powerful radio telescopes (SKA, and its precursor MeerKAT in South Africa) and their correlation with the largest gamma-ray telescopes in Southern Africa (HESS in Namibia and the future Cherenkov Telescope Array – CTA) to unveil the structure, origin and evolution of the Universe and of its sub-structures, from the smallest galaxies to the largest galaxy clusters.

In this context, Prof Colafrancesco has a wide range of research interests, among which the search for the nature of dark matter, the origin of dark energy, probes of gravity on cosmological scales, the origin of cosmic magnetism, the multi-scale evolution of galaxies and galaxy clusters, the nature of the most powerful objects in the Universe (blazars and radio-galaxies), the origin of high-energy phenomena and magnetic fields in cosmic structures, the origin of cosmic rays and the nature of the highest-E particle events in the Universe. He is also currently exploring new directions in the astrophysical studies of light propagation and quantum space-time effect.

Contact details: sergio.colafrancesco@wits.ac.za / +27 (0)11 717 6823