Dr Cynthia Chiang, Senior Astrophysics lecturer at the UKZN Astrophysics and Cosmology Research Unit, has returned from Marion Island, situated halfway between Antarctica and South Africa, where she upgraded the PRIZM radio telescope.
The telescope, built by Chiang and her Astrophysics students, is being used to detect traces of the first stars that “turned on” in the universe.
Earlier this year, Chiang – assisted by some of her students – added two additional antennaes to the telescope in the team’s first visit to the island since installing the telescope in 2017. The two new antennas are of a different design and operate at lower frequencies to the existing ones.
Later, Chiang returned to Marion Island alone and repaired a portion of the telescope with the help of specialists based on the island. She also renewed 500kg of batteries to increase the lifespan of the experiment.
PRIZM (Probing Radio Intensity at high-Z from Marion) is a low-frequency radio telescope which collects information about the universe during the Cosmic Dawn, the period a few hundred million years after the big bang when the first stars in the universe formed. The light from these first stars is too dim for optical telescopes to view, therefore, they have never been measured directly. PRIZM was designed to make this measurement and to help determine when the first stars and galaxies formed.
In order to effectively capture data, the chosen site for the telescope had to be in an area free from man-made transmissions such as radio stations and cell phones. Marion Island was chosen due to its ideal remote location which is more than 2 000km away from the nearest continental landmasses and in one of the most radio silent locations in the world.
Chiang and her team experienced many challenges while working on the island which lies in the Roaring Forties, an area notorious for high winds, rain and cold temperatures and accessible only by sea. The SA Agulhas II, which is a South African icebreaking polar supply and research ship owned by the Department of Environmental Affairs, visits once a year. In addition, stays on the island must be short. ‘We had a very compressed timeline of three weeks on the island to set up, get the equipment running, capture the data and leave,’ said Chiang. ‘Sometimes weather and logistic delays gave us even less time to get things done,’ she added.
The PRIZM telescope has been collecting data for the past year on Marion Islandand Chiang and her students are currently processing data collected during this period. ‘With this telescope, we receive true signals from the sky as well as environment and systematic effects that might be introduced by an instrument, therefore, there is a lot of work involved in separating these effects making sure we understand that what we’re seeing is the actual truth from the sky,’ she said.
Chiang, who has also contributed to other telescopes across the world, including SPIDER, Planck High-Frequency Instrument, South Pole Telescope and C-BASS, said Marion Island is the toughest assignment she has had. ‘You’re cold, tired, hungry and exhausted all the time but it is absolutely worth it for the science and it is such a beautiful location as well,’ she said.
Words: Bavani Naidoo
Photograph: Supplied by Dr Cynthia Chiang