Exploring the Cosmic Dawn!

UKZN research team members (from left) Mr Heiko Heilgendorff,
Ms Ridhima Nunhokee, Dr Cynthia Chiang, and Mr Liju Philip.
(Right) the team assembling the 70MHz antennae.

A UKZN research team has returned from a trip to Marion Island in the sub-Antarctic Indian Ocean where they conducted work on Probing Radio Intensity at high-Z from the Marion (PRIZM) telescope.

The team comprised a senior lecturer at the Astrophysics and Cosmology Research Unit, Dr Cynthia Chiang, and Astrophysics PhD students Mr Liju Philip, Ms Ridhima Nunhokee and Mr Heiko Heilgendorff.

PRIZM 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 see thus they have never been measured directly. PRIZM is designed to make this measurement and data received could help in determining when the first stars and galaxies formed.

PRIZM observes the average brightness of the sky below 250 MHz.  At these frequencies, it is impossible to get clear readings in populated areas due to interference from man-made radio signals. FM radio stations, for example, operate between 88 and 108 MHz, which is right where the cosmic dawn signal is expected to peak.

In their quest to capture uncontaminated data, the astronomy team selected Marion Island as the location for the telescope as it is separated from the nearest continental landmasses by 2 000km and is one of the most radio silent locations in the world.

The only access is via the SA Agulhas which sails to and from the island once a year. The island lies in the Roaring Forties, an area notorious for high winds and rain which posed new challenges for the team in setting up their equipment. In addition, the team had only three weeks to get everything up and running. However, in spite of these hurdles they succeeded in deploying two new antennas on the PRIZM telescope observing at 70 and 100 MHz.

‘Marion Island is a fantastic new location for radio astronomy, and we’re very excited to see the data from our year of observations,’ said Chiang. ‘The telescope worked beautifully thanks to hard work from the whole team, especially the students who participated in the voyage and who relentlessly braved the long hikes and harsh weather to get the science done!’

Exploring Marion Island as a new place for low frequency astronomy is exciting as the island may actually provide the best place to observe ultra-low frequencies (10 MHz). If researchers can get to those low frequencies, it would be possible to start looking back to an earlier time in history, such as the Dark Ages – the period before the Cosmic Dawn.

To date, astronomers have not been able to access such information from that time due to difficulties in obtaining measurements.

The latest UKZN venture was the first astronomy project to operate on Marion Island and could pave the way for similar projects there in the future.

Merissa Naidoo

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