Explorer of outer frontier detects faint sound of galaxy radio halo

22 July 2016 - 20:42 By Tmg Digital

A radio halo in a galaxy cluster has been discovered by a researcher at the University of KwaZulu-Natal’s Astrophysics and Cosmology Research Unit.

Evidence of Kenda Knowles’ detection was published this month in “Monthly Notices of the Royal Astronomical Society”‚ an international peer-reviewed astronomy journal.Radio halos are transient and relatively rare. They are large regions in clusters of galaxies which emit radio waves. The emission brightens during the merger and then fading away - on timescales of a few billion years. The emissions are very faint and need sophisticated data processing techniques to detect.This composite image of the cluster shows data from three different wavelengths. The background colour shows the galaxies, with those belonging to the cluster appearing yellow. The hot cluster gas is overlaid in pink, and the newly detected radio halo in green. Image: UKZNKnowles‚ who received her PhD from UKZN earlier this year‚ was funding by the Square Kilometre Array South Africa bursary programme."Radio halos are fascinating objects to study as they probe the non-thermal components of galaxy clusters‚ such as magnetic fields‚ which are difficult to study at other astronomical wavelengths‚” she said. “Their link to merging activity of the host galaxy cluster makes them a powerful tool to investigate the physical processes that occur during these energetic events."She added that although the detection is quite exciting‚ the new aspect is the estimation of a timescale for the radio emission.Knowles and her collaborators used data from the Giant Metrewave Radio Telescope in India. The sample of galaxy clusters was discovered by the Atacama Cosmology Telescope in Chile‚ a project in which the UKZN group is involved.Kavilan Moodley‚ a co-author and Knowles's PhD thesis advisor‚ said: "By combining observations of this galaxy cluster from telescopes operating at three different wavelengths‚ Kenda was able to deduce that the radio halo we detected is a relatively young one‚ and has still to reach its maximum power."The MeerKAT telescope being built by SKA South Africa in the Northern Cape will help this area of research because it can provide excellent sensitivity to faint sources...

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