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SA astronomers catch glimpse of early universe

Read time 5min 10sec
The new discovery will help in exploring what the universe of tomorrow will be like.
The new discovery will help in exploring what the universe of tomorrow will be like.

South African astronomers scored another first when they caught a glimpse of the early universe by chance.

Using deep radio imaging, researchers at the University of Cape Town (UCT) and University of the Western Cape (UWC) revealed that supermassive black holes in a region of the distant universe are all spinning out radio jets in the same direction - most likely a result of primordial mass fluctuations in the early universe.

According to the astronomers, the new discovery offers a glimpse of the early universe to be revealed when the Square Kilometre Array (SKA) is operational.

The new discovery comes when the local astronomy industry is making some groundbreaking findings. In February, two local researchers played a big part in making a groundbreaking discovery by peering through the stars and dust of the Milky Way with a radio telescope to discover hidden galaxies beyond.

Local astronomer Kevin Govender from the Cape Town-based Office of Astronomy for Development and the International Astronomical Union also became the first South African to be awarded at the 2016 Edinburgh International Science Festival.

Radio galaxies

The new result is the discovery - for the first time - of an alignment of the jets of radio galaxies over a large volume of space, a finding made possible by a three-year deep radio imaging survey of the radio waves coming from a region called ELAIS-N1 using the Giant Metrewave Radio Telescope (GMRT).

The radio jets are produced by the supermassive black holes at the centres of these galaxies, and the only way for this alignment to exist is if supermassive black holes are all spinning in the same direction, says professor Andrew Russ Taylor, joint UWC/UCT SKA chair, director of the recently-launched Inter-University Institute for Data Intensive Astronomy and principal-author of the study.

"Since these black holes don't know about each other, or have any way of exchanging information or influencing each other directly over such vast scales, this spin alignment must have occurred during the formation of the galaxies in the early universe," he notes.

This implies there is a coherent spin in the structure of this volume of space that was formed from the primordial mass fluctuations that seeded the creation of the large-scale structure of the universe, he adds.

With study co-author - and UCT PhD student currently working at the National Radio Astronomy Observatory, Socorro, New Mexico, US - Preshanth Jagannathan, the team discovered the alignment after the initial image had been made. Within the large-scale structure, there were regions where the spin axes of galaxies lined up.

Detecting deviations

The finding wasn't planned for - the initial investigation was to explore the faintest radio sources in the universe, using the best available telescopes - a first view into the kind of universe that will be revealed by the South African MeerKAT radio telescope and the SKA, the world's most powerful radio telescope and one of the biggest scientific instruments ever devised.

The researchers explain that earlier observational studies had previously detected deviations from isotropy in the orientation of galaxies. But these sensitive radio images offer a first opportunity to use radio jets to reveal alignments of radio galaxies on physical scales of up to 100Mpc.

Measurements from the total intensity radio emission of AGN jets have the advantage of not being affected by propagation effects such as scattering, extinction and Faraday Radiation, which may be an issue for optical and polarimetric studies, they note.

They point out the presence of alignments and certain preferred orientations can shed light on the orientation and evolution of the galaxies.

"So what could these large-scale environmental influences during galaxy formation or evolution have been? Taylor asks. "There are several options - cosmic magnetic fields, axionic fields post-inflation, and cosmic strings are only some of the possible candidates that could effect an alignment in galaxies even on scales larger than galaxy clusters."

It would be interesting to compare this implication with predictions of angular momentum structure from universe simulations, he points out.

Bizarre finding

UWC professor Romeel Dave, SARChI chair in Cosmology with Multi-Wavelength Data, who leads a team developing plans for universe simulations that could explore the growth of large-scale structure from a theoretical perspective, agrees.

"This is not obviously expected based on our current understanding of cosmology. It's a bizarre finding. It's a mystery, and it's going to take a while for technology and theory alike to catch up."

The researchers note such imaging projects are in the planning stages for the SKA and its precursor telescopes, the South African MeerKAT array and the Australian SKA Pathfinder.

"GMRT is one of the largest and most sensitive radio telescope arrays in the world," notes Taylor.

"However, we really need MeerKAT to make the very sensitive maps, over a very large area and with great detail, that will be necessary to differentiate between possible explanations. It opens up a whole new research area for these instruments, which will probe as deeply into the universe and as far back as we can go - it's going to be an exciting time to be an astronomer.

"We're beginning to understand how the large structure of the universe came about, starting from the Big Bang and growing as a result of disturbances in the early universe, to what we have today," says Taylor. "That helps us explore what the universe of tomorrow will be like."

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