DARA Science Talks

VLBI Observations of Faint (μJy) Extragalactic Radio Sources-The wide-field VLBA & EVN GOODS-N 1.4 GHz surveys
Presenter - Ann Njeri (U. Manchester)
Abstract - A combination of sensitivity and high angular resolution imaging over a range of spatial scales (arcsec to mas) is required to understand the star formation history (SFH) and its evolution with cosmic time, thus characterizing relative contribution of radio emission associated with either star-formation or AGN in galaxies. This and a range of galaxy evolution topics are uniquely and robustly being tackled through wide-field VLBI surveys. I will present results from deep wide-field VLBI surveys of the GOODS-North field with the EVN and the VLBA combined with the lower arcsec resolution study of the same field with the JVLA and the e-MERLIN, which provide deep and high spatial dynamic range from (arcsec to mas resolutions) observations for; i) the robust determination of the compact radio AGN components; ii) the first multi-resolution view of the transition between compact AGN and diffuse SF radio components; and iii) contribute to multiple key technical verifications relevant to SKA-pathfinders and VLBI itself and thus aid in the planning of future SKA(-VLBI) deep surveys

Science with the MIGHTEE survey
Presenter - Dr I. Whittam (University of Oxford / University of the Western Cape)

Protoplanetary disks in the interferometric age
Presenter - Dr C. Walsh (University of Leeds)

Edutaining Astronomy
Presenter - Prof Peter Barthel (University of Groningen)
Abstract - Basic understanding of earth and sky are valuable elements towards global citizenship. Moreover, the sky is beautiful, fascinating, and mighty interesting - and it is there for everyone! Teaching children and lay people about astronomy can be easy and rewarding. Effective science education and public outreach is built on two simple words, which I will discuss. After a general introduction on astro-edutainment I will focus on a celestial body we all know and love: our moon. Towards the end of the talk I will discuss the moon as it is depicted in children’s books and on Christmas cards, and demonstrate with a smile that there is always something to learn! (Talk hosted by the University of Pretoria).

Observing the Milky Way with a Table-Top Radio Telescope Part 2: Making the observations
Presenter - Prof Peter Wilkinson, University of Manchester, UK
Abstract - The study of atomic hydrogen throughout the universe was one of the prime scientific drivers for the SKA and I’ve long wanted to offer DARA students, and potential future recruits, the chance to make their own hydrogen line observations. Introductory work is often based on parabolic dishes ~3m in diameter, which are expensive. The low-cost Table-top Radio Telescope (TTRT) is much smaller but its sensitivity is sufficient to give students the thrill of observing clouds of galactic hydrogen and detecting the differential rotation of the Milky Way. In e-seminar #1 I described the principles of 21cm hydrogen line observations and how radio astronomers revealed that the Milky Way has spiral arms. In e-seminar #2 I will describe the TTRT equipment and how to take, calibrate and analyse the data it produces. Some results of Milky Way observations made from my garden in the UK will be presented.
This is NOT a quick-look “gee whizz” experiment but a real introduction to radio astronomy observations and data reduction. Students will have to work carefully and systematically to get reliable, quantitative, results. The aim of this seminar is to provide students with a confidence-building pathway so that, working with the explanatory script, they will be able to use the TTRT with the minimum of supervision.

AI and Bias in Radio Astronomy
Presenter - Prof Anna Scaife, University of Manchester, UK
Abstract - The expected volume of data from the new generation of scientific facilities such as the Square Kilometre Array (SKA) has motivated the expanded use of semi-automatic and automatic machine learning algorithms for scientific discovery in astronomy. In this field, the robust and systematic use of machine learning faces a number of specific challenges including (i) a paucity of labelled data for training - paradoxically, although we have too much data, we don't have enough, (ii) a clear understanding of the effect of biases introduced due to observational and intrinsic astrophysical selection effects in the training data, and (iii) the quantitative statistical representation of outcomes from decisive AI applications that can be used in scientific analysis. In this seminar I will discuss the motivations and potential for using AI solutions in astronomy, with particular reference to radio astronomy and the SKA, and how the extreme data rates of next generation instrumentation are driving automation in scientific analysis. I will also talk about the inherent biases that AI methods can introduce, why astronomy data may be particularly susceptible to these problems and discuss some of the potential methods for quantifying, understanding and mitigating the effect of these biases.

Astronomy at Low Frequencies: Prospects of the LOFAR System
Presenter - Dr. Bernard Duah Asabere, ASTRON in The Netherlands & GSSTI in Ghana
Abstract - LOFAR, the LOw-Frequency ARray, is a multi-purpose new-generation radio telescope distributed throughout the Netherlands and in several countries in Europe. It was designed, constructed and being operated by ASTRON (Netherlands Institute for Radio Astronomy) on behalf of the International LOFAR Telescope (ILT) foundation. LOFAR consists of an interferometric array of dipole antenna stations, which utilize a novel phased-array design. It covers the mostly unexplored low-frequency range from 10 – 240MHz and provides a number of unique observing capabilities. The digital beam-forming techniques it uses make the LOFAR system agile for rapid repointing, which makes it suitable for multiple simultaneous observations. With its dense core array and long interferometric baselines, LOFAR achieves unprecedented sensitivity and angular resolution in the low-frequency radio regime. And as an observatory, it is opened to the global astronomical community. The capabilities, techniques and modus operandi make LOFAR a key pathfinder of the global Square Kilometre Array (SKA). In this talk, I will give an overview of the LOFAR system, major hardware and software components, how it operates, the observing modes and the key science projects that have driven its design and construction. I will present an outline of how to join the LOFAR user community, apply for observing time and access the incredibly huge amount of datasets in the LOFAR Long Term Archive (LTA). I will also highlight the available training, developments and research opportunities at ASTRON and potentials for collaborations. And as well, mention the future of ASTRON and LOFAR2.0.

The Radio Milky Way
Presenter - Prof Mark Thompson, University of Hertfordshire, UK
Abstract - The Milky Way as seen in the sky shows a view through the central plane of our spiral galaxy. Most of our view of the galaxy is blocked by clouds of interstellar gas and dust, but radio waves can cut through this obscuration and reveal the hidden side of star formation and stellar evolution. In this seminar I will take you though the history of Galactic Plane radio surveys and go through some of the latest results from the JVLA and MeerKAT telescopes.

First results and potential African expansion of the Event Horizon Telescope
Presenter - Associate Prof Roger Deane, University of Pretoria, SA
Abstract - On 10 April 2019, the Event Horizon Telescope Collaboration revealed the first image of a black hole. This required a large international effort by over 200 scientists spread across five continents. The team uses a technique called radio interferometry, synthesising a virtual telescope with the effective diameter of the Earth - a technique known as Very Long Baseline Interferometry (VLBI). By using antennas with separations on inter-continental scales, and observing a wavelength of light of 1 mm, the team is able to achieve an effective angular resolution of ~20 micro-arcseconds (the apparent size of a doughnut on the moon). Apart from providing visual confirmation of the existence of black holes, the size and shape of the shadow feature could in future provide a stringent test of Einstein’s General Theory of Relativity in the strong-field regime. In this DARA e-seminar, I will provide an overview of the instrument and the key scientific results, as well as looking to the future of this exciting field, including the possible expansion of the array onto African soil.

#6: Observing the Milky Way with the Table-Top Radio Telescope
Presenter - Prof Peter Wilkinson, University of Manchester, UK
Abstract - The study of atomic hydrogen in the far reaches of universe was one of the prime scientific drivers for the SKA and I’ve long wanted to offer DARA students, and potential future recruits, the chance to make their own hydrogen line observations - though obviously on a smaller scale! Even so introductory work is often based on parabolic dishes ~3m in diameter and these may be too expensive for universities to acquire. The Table-Top Radio Telescope (TTRT) is therefore deliberately small but its sensitivity remains sufficient to give students the real-time thrill of observing clouds of hydrogen gas thousands of light years away and detecting the rotation of the Milky Way. Twenty TTRTs will be supplied by DARA for use in partner countries. The aim is to make the instrument usable with limited supervision and so, to complement the instruction booklet which comes with the TTRT, I’m giving two e-seminars to provide an additional confidence-building pathway.
Part 1 introduces the principles of 21cm hydrogen line observations and describes how radio astronomers over 60 years ago were able to show that the Milky Way has spiral arms. Some of the latest results on the Milky Way and nearby galaxies will also be presented.

Space Science and Technology for Growth - AVN and Colocation
Presenter - Carla Sharpe, SARAO, Jul 7 2020
Abstract - In 2012, South Africa initiated the AVN programme with eight African Partner countries; Botswana, Ghana, Kenya, Madagascar, Mauritius, Mozambique, Namibia and Zambia. The long term purpose of the AVN programme is to establish Very Long Baseline Interferometry (VLBI) capable radio telescopes in the SKA African partner countries (APC). This will enable scientific advancement through the transfer of knowledge and technology as well as the development of transferable skills within participating countries. Space science and space exploration are generally undertaken for the benefit of humanity and thus are normally regarded as a public good provided at a cost to national governments. The space industry, however, although utilising space science and providing for further scientific development, is revenue-driven and provides goods and services to clients, both private and public. By colocating space science and space industry infrastructure, self sustaining sites can be developed with the potential for knowledge sharing and innovation.

Reflections Ahead of Considering Starting a Business
Presenter - Steve Jones, University of Leeds
Abstract - A personal view of the processes involved in conceiving, planning, and delivering a successful Business Plan. This talk is to support business-up ideas, mainly linked to the skills developed during DARA training, although not exclusively so. The talk will provide a framework of prompted questions on an effective approach to deal with:
Why am I considering starting a business? Goal Setting and Risk Management from the outset. No substitute for Market Research – the hard yards. Forecasting, cash flow and how to evaluate whether this is a sound business case.What are funders will be looking for and why you will be ready.

Non-thermal radio emission from massive protostellar jets
Presenter - Prof Benjamin Stappers, Jodrell Bank - University of Manchester, 28 May 2020
Abstract - In 2007 Astronomers discovered a very bright burst of radio emission which lasted just a few milliseconds which originated far outside of our own galaxy. The extreme brightness and the very short duration indicate that the source must be highly energetic and mostly likely associated with a black hole or neutron star. Another possibility is that they are caused by some cataclysmic event, like the collapse of a neutron star to form a black hole or the merger of two neutron stars. As these bursts travel great distances through space they are potentially great probes of the material and space between us and their origin helping us to understand more about the missing mass and energy in the Universe. There are now dozens of these bursts known and the race is on to find many more with new and existing telescopes around the world. I will discuss some of the history of FRBs, our current understanding, and look forward to the future including possibilities for South Africa’s very own MeerKAT telescope.

Non-thermal radio emission from massive protostellar jets
Presenter - Dr Willice Obonyo, University of Leeds - Former DARA PhD, 6 May 2020
Abstract - I will present the main results from my PhD work funded by DARA at the University of Leeds and briefly describe my journey from Kenya, through the DARA programme and my next steps. Massive protostars drive out jets of material, which may be magnetically or radiatively driven. A search for synchrotron emission, associated with magnetised jets, was conducted on a sample of massive protostars, observed using the JVLA at 1.5 GHz. The emission from the objects was characterised using their spectral indices and spectral index maps, calculated from the 1.5GHz data, and previous observations at 6.0GHz and 44GHz. All the cores of the jets were found to be thermal, however, forty per cent of the jets have non-thermal lobes which are associated with synchrotron emission. Some of the sources in the sample displayed evidence of variability. Besides observations, free-free emission from the jets' cores was simulated using hydrodynamics and ray-tracing codes.

DARA - Now and future
Presenter - Prof Melvin Hoare (U. Leeds/ DARA Principal Investigator)
Abstract - I will outline the aims of this new e-seminar series and invite suggestions for topics for future e-seminars. I will briefly describe the current status of the DARA project as we approach the end of the second phase of the project. As with every other aspect of life at the moment the basic training programme is being delayed by about one year, but we still aim to complete the whole programme as originally planned. Recent developments in and around the DARA project include Masters students in Mauritius, the Business Consultant to provide advice and starting a business, and aligning with the new emphasis on the co-location of space related activities and radio astronomy under the African Programme coming from our South African partners, SARAO. I will also outline our current thinking for the next phase of DARA that we hope to bid for funding for over the next couple of years. This will include support for the teaching of astrophysics at undergraduate level in African universities, more Masters and PhDs in the UK and Africa and a new focus on postdoctoral fellows in African universities. We very much hope you will be able to join us to provide your input via questions at the end of the e-seminar.