Characterising radio sources in the Small Magellanic Cloud using citizen science and optical spectroscopy

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dc.contributor.advisorMcbride, Vanessa
dc.contributor.authorDe Beer, Gideon
dc.date.accessioned2025-11-17T12:51:28Z
dc.date.available2025-11-17T12:51:28Z
dc.date.issued2025
dc.date.updated2025-11-17T12:45:58Z
dc.description.abstractFor several years, the Small Magellanic Cloud (SMC) has been extensively studied in multiple wavelengths, revealing rich populations of radio sources within and beyond the nearby dwarf galaxy. With radio interfer-ometers' ever-increasing sensitivity and resolution, greater source populations will be discovered. Two regions of the SMC dwarf galaxy were observed using MeerKAT, with 10873 radio sources identified across them. In this dissertation, we characterise the radio source population of these two regions. This was approached using citizen science and optical spectroscopic follow-up. From the 10873 radio sources, 1429 were selected as subjects for classification in the citizen science project. This selection was based on the radio signal-to-noise ratio. The citizen science approach used information from the radio images, combined with optical cutouts from the SuperCOSMOS Sky Survey. The results show a high level of agreement among volunteer classi-fiers on questions concerning basic morphological characteristics. Around 63 per cent of all classifications show complete agreement between at least 5 classifiers in determining whether the displayed source was a radio point or an extended source and whether there is a likely optical counterpart aligned with the radio emission for the 1429 subjects. 41 radio sources were selected from the original 10873 for spectroscopy, by cross-matching the radio source list to the GAIA optical catalogue and making a magnitude cut. Optical spectroscopic follow-up of 23 sources from these 41 was conducted in November 2023. The reduced spectra from the observations were analysed to identify the optical sources, determine whether the optical and radio emissions were coincident, and identify what mechanism might be causing the radio emission if the optical source is considered likely to be the optical counterpart to the radio source. Characterisation revealed 13 stars, 3 eclipsing binaries and 2 nebulae. Between the two analysis methods, with their own independently se-lected source sample pools, 6 sources were found to overlap. The resultant analysis between the methods gave complementary source characterisation results. Approximately 912 radio sources have been characterised in total, at least by radio morphology and the likely presence of an optical counterpart, during this project.
dc.identifier.apacitationDe Beer, G. (2025). <i>Characterising radio sources in the Small Magellanic Cloud using citizen science and optical spectroscopy</i>. (). University of Cape Town ,Faculty of Science ,Department of Astronomy. Retrieved from http://hdl.handle.net/11427/42235en_ZA
dc.identifier.chicagocitationDe Beer, Gideon. <i>"Characterising radio sources in the Small Magellanic Cloud using citizen science and optical spectroscopy."</i> ., University of Cape Town ,Faculty of Science ,Department of Astronomy, 2025. http://hdl.handle.net/11427/42235en_ZA
dc.identifier.citationDe Beer, G. 2025. Characterising radio sources in the Small Magellanic Cloud using citizen science and optical spectroscopy. . University of Cape Town ,Faculty of Science ,Department of Astronomy. http://hdl.handle.net/11427/42235en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - De Beer, Gideon AB - For several years, the Small Magellanic Cloud (SMC) has been extensively studied in multiple wavelengths, revealing rich populations of radio sources within and beyond the nearby dwarf galaxy. With radio interfer-ometers' ever-increasing sensitivity and resolution, greater source populations will be discovered. Two regions of the SMC dwarf galaxy were observed using MeerKAT, with 10873 radio sources identified across them. In this dissertation, we characterise the radio source population of these two regions. This was approached using citizen science and optical spectroscopic follow-up. From the 10873 radio sources, 1429 were selected as subjects for classification in the citizen science project. This selection was based on the radio signal-to-noise ratio. The citizen science approach used information from the radio images, combined with optical cutouts from the SuperCOSMOS Sky Survey. The results show a high level of agreement among volunteer classi-fiers on questions concerning basic morphological characteristics. Around 63 per cent of all classifications show complete agreement between at least 5 classifiers in determining whether the displayed source was a radio point or an extended source and whether there is a likely optical counterpart aligned with the radio emission for the 1429 subjects. 41 radio sources were selected from the original 10873 for spectroscopy, by cross-matching the radio source list to the GAIA optical catalogue and making a magnitude cut. Optical spectroscopic follow-up of 23 sources from these 41 was conducted in November 2023. The reduced spectra from the observations were analysed to identify the optical sources, determine whether the optical and radio emissions were coincident, and identify what mechanism might be causing the radio emission if the optical source is considered likely to be the optical counterpart to the radio source. Characterisation revealed 13 stars, 3 eclipsing binaries and 2 nebulae. Between the two analysis methods, with their own independently se-lected source sample pools, 6 sources were found to overlap. The resultant analysis between the methods gave complementary source characterisation results. Approximately 912 radio sources have been characterised in total, at least by radio morphology and the likely presence of an optical counterpart, during this project. DA - 2025 DB - OpenUCT DP - University of Cape Town KW - Small Magellanic Cloud KW - Optical spectroscopy LK - https://open.uct.ac.za PB - University of Cape Town PY - 2025 T1 - Characterising radio sources in the Small Magellanic Cloud using citizen science and optical spectroscopy TI - Characterising radio sources in the Small Magellanic Cloud using citizen science and optical spectroscopy UR - http://hdl.handle.net/11427/42235 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/42235
dc.identifier.vancouvercitationDe Beer G. Characterising radio sources in the Small Magellanic Cloud using citizen science and optical spectroscopy. []. University of Cape Town ,Faculty of Science ,Department of Astronomy, 2025 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/42235en_ZA
dc.language.isoen
dc.language.rfc3066eng
dc.publisher.departmentDepartment of Astronomy
dc.publisher.facultyFaculty of Science
dc.publisher.institutionUniversity of Cape Town
dc.subjectSmall Magellanic Cloud
dc.subjectOptical spectroscopy
dc.titleCharacterising radio sources in the Small Magellanic Cloud using citizen science and optical spectroscopy
dc.typeThesis / Dissertation
dc.type.qualificationlevelMasters
dc.type.qualificationlevelMSc
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