About my self.

Walter Silima

I am Walter Silima, currently appointed as an Astrophysics (AST2002H) tutor, a second-year course at the University of Cape Town. I am a registered MSc (Astrophysics and Space Science) student at the University of Cape Town and a research affiliate at University of the Western Cape. I have completed my honours degree in the first class (2020) at the University of Cape Town. I am a Cum Laude graduate from the University of Limpopo. I was awarded a merit bursary that covered my tuition fees for my first-year courses for achieving a minimum requirement of 70% from my grade 12 examination results. During my second year, I was awarded a merit bursary for achieving a minimum requirement of 70% from my first-year results; this covered only my registration fees at the university and for my final year I was awarded a merit bursary that covered my tuition fees for achieving a minimum requirement of 76% from my second-year courses. I have earned many certificates of excellence from primary school more especially in mathematics and physics. After I completed my degree I decided to apply for the National Astrophysics and Space Science (NASSP) program at the University of Cape Town. In 2019 I enrolled at the University of Cape Town for the miscellaneous courses towards a postgraduate degree namely the Honours in Astrophysics and Space Science where I also managed to obtain an average of 77.5%, the modules for which I enrolled. In June 2018, I attended the National Astrophysics and Space Science Program (NASSP) winter school which took place in Cape Town, South Africa where I co-presented a paper on photometry of Known Delta Scuti stars. In February 2020 I attended the South African National Space Agency summer school. I was also selected to be one of the 8 students from South Africa to attend the SANSA Space Science International Space Weather Camp (ISWC) 2020 to be held in Hermanus, South Africa, the University of Huntsville (Alabama, USA) which was going to take place from 21 June – 19 July 2020 but was cancelled due to the coronavirus pandemic.

I have realised that astrophysics is one of the fields which requires one to obtain at least a PhD to be considered a professional astronomer. I have chosen this career path for myself and it is now my responsibility to make sure that I reach my goal. I want to make sure that in my journey to PhD I learn not only about this field, but I also learn how to interact with people from different cultures, race, beliefs, etc. It is from this diverse knowledge that I believe I can be the best student, researcher and can change the world. Radio astronomy is the science that I admire the most because it focuses on extragalactic objects and it involves a lot of computations. It is in my heart to take part in the big astronomical telescope such as the Square Kilometer Array (SKA) telescope. I want to be part of the group of astronomers that will be analysing the vast amount of data coming from the SKA and having acquired the diversity skills will make me a force in a team since I will be bringing the experience and creativity.which enables me a problem solver if we encounter new challenges.

My Academic Research Expertise.

I am currently working on machine learning techniques to classify radio sources from their corresponding multi-wavelength data. This is an interesting and developing field of astronomy since as a result of recent advances in astronomical and digital technologies, astronomy is rapidly becoming a data-rich science. The much-increased data rates from radio surveys with MeerKAT, ASKAP, and eventually the Square Kilometre Array, require the adoption of machine-learning techniques to automate most tasks previously carried out by astronomers. One such task is classifying radio sources as star-formation- or accretion-dominated. I am interested in implementing and optimising supervised machine learning techniques for the classification of radio sources detected in the MIGHTEE survey.

I have a particular interest in extragalactic astronomy and machine learning for astronomy. For my honours project I have used Machine Learning In Multi-Wavelength Galaxy/Quasar Evolution (Photometric Redshift Estimation) where we used the supervised machine learning algorithms (K-Nearest Neighbour and Random Forest) to estimate the photometric redshifts of the galaxies and quasars under the supervision of Prof. Mattia Vacarri. The photometric redshifts of galaxies were derived using their magnitudes measured in different filters and also using the spectroscopic redshifts as the true redshifts of the sources. In this project we have demonstrated that simple machine learning algorithms can handle large amount of data and are very efficient when estimating photometric redshifts.

I have also went on to optimise the hyperpametes of Random Forest and XGBoost as a continuation of the honours project above. This was because we did not have enough time to complete the whole project in the provided time. In this case, we trained the algorithms on about 80% of the dataset to find the best parameter settings for the algorithms to best estimate the photometric redshifts using the sk-learn RandomisedSearchCV. We used the scoring metris neg median absolute error, neg mean squared error and both algorithms. The details of both projects can be accessed on my github account below.

pfunzowalter github account

Work experience


2020 - Current

University of Cape Town

Student tutor ( Astrophysics (AST2002H))


December 2020 - February 2021

Davhana Secondary School

Education assistance


February - May 2018

University of Limpopo

Sinior lab assistance for first-year students


February - December 2018

University of Limpopo

Peer counsellor at Centre for Students Counseling and Development

Education


Current

The University of Cape Town, Department of Astronomy

Master’s (Astrophysics), National Astrophysics and Space Science Program (NASSP)


current

University of the Wastern Cape, Department of Astronomy

Master’s Research Affiliate Student Astrophysics


February 2020 - December 2020

The University of Cape Town, Department of Astronomy

Honours (Astrophysics), National Astrophysics and Space Science Program (NASSP)


February 2019 - December 2019

The University of Cape Town, Department of Astronomy

Post Graduate Bridging Program (Astrophysics), National Astrophysics and Space Science Program (NASSP)


February 2016 - December 2018

University Of Limpopo, School of Physical and Mineral Science

Bachelor of Science (Physics and Chemistry)

Cum Laude, 2016 and 2018 merit award in recognition

of obtaining an average of 70 percent and above.