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$9.5m boost for Karoo's Hera telescope

Read time 4min 20sec
Hera currently has 19 14m radio dishes at the SKA South Africa Losberg site.
Hera currently has 19 14m radio dishes at the SKA South Africa Losberg site.

The US National Science Foundation has provided $9.5 million funding to the Hydrogen Epoch of Reionisation Array (Hera) telescope in the Karoo to view the universe's first stars and galaxies.

Hera is located only a few kilometres from the MeerKAT radio telescope, which began initial science operations in July, marked by Department of Science and Technology minister Naledi Pandor.

Hera, which was recently granted the status of a Square Kilometre Array (SKA) precursor telescope, currently has 19 14m radio dishes at the SKA South Africa Losberg site near Carnarvon. These will soon be increased to 37. The $9.5 million in new funding will allow the array to expand to 220 radio dishes by 2018.

This telescope aims to detect the distinctive signature that would allow astronomers to understand the formation and evolution of the very first luminous sources - the first stars and galaxies in the universe. The Hera radio telescope follows in the footsteps of a precursor instrument called Paper (Precision Array for Probing the Epoch of Reionisation) also located in the Karoo.

Billion-year exploration

The much more sensitive Hera, operating in the Karoo with minimal man-made radio interference, will explore the billion-year period after hydrogen gas collapsed into the first galaxies, a few hundred million years after the big bang, through the ignition of stars throughout the universe - the first structures of the universe we observe today.

"The Universe was formed in a hot big bang of particles and radiation 14 billion years ago, but soon cooled down and was dark for hundreds of millions of years, before any stars formed. Nobody yet knows when these stars formed," explains Dr Fernando Camilo, SKA SA chief scientist.

"The funding increases the chances that signs of the first stars and galaxies ever to be created will soon be detected - in South Africa' s Northern Cape."

He points out that 400 000 years after the big bang, the universe was largely made up of neutral hydrogen, the simplest and most common element. Eventually, he notes, while the universe at large expanded, ever-larger clouds of hydrogen gathered due to their mutual gravitational attraction.

In time, some of these clouds became dense and hot enough that hydrogen atoms fused and the first stars formed, says Camilo. He adds these first brilliant objects flooded the universe with ultraviolet light that split or ionised all the hydrogen atoms between galaxies into protons and electrons - the beginning of cosmic reionisation.

"Hera - which operates at low radio frequency - has enough sensitivity to detect cosmic reionisation and we hope to map it very precisely by statistically measuring how the fraction of neutral hydrogen changed with cosmic time. Hera has the potential to transform our knowledge in one of the main SKA science areas," says Dr Gianni Bernardi, SKA SA senior astronomer.

Inexpensive structure

SKA SA notes the work is all the more impressive because the telescope's minimalist design makes it a relatively inexpensive structure. Because each antenna will point in a fixed direction, they do not have to move around, so no expensive moving parts are required, the organisation points out.

"Hera is a truly Karoo-based instrument. Construction materials are sourced and fabricated from within South Africa - predominantly from the Carnarvon area," says Kathryn Rosie, project engineer. "Because the bulk materials of construction are light industry materials such as wood and PVC pipe, there is opportunity for local businesses, which don't necessarily have a 'high technology' customer base, to be a part of this awesome science instrument. We have local contractors installing our main support poles, cutting our structural elements to size, and making up our reflector surface panels from bulk supplied material," says Rosie.

On connecting Hera to MeerKAT, Dr Rob Adam, SKA SA MD, says: "Among other investigations, MeerKAT will study evolved galaxies in the later universe, while Hera will peer back nearer to the dawn of time, when the first stars and galaxies were being formed. In this way, they address complementary scientific questions."

In the next decade, MeerKAT will become integrated into SKA1-MID, Southern Africa's portion of the largest astronomical project, the Square Kilometre Array. This will be complemented by SKA1-LOW to be built in Australia, which in turn will study in much greater detail the pioneering detections expected from HERA.

Hera is one of a number of low frequency telescopes, including the Murchison Widefield Array in Australia and the Low Frequency Array in the Netherlands that are pathfinders for SKA1-LOW to be located in Australia.

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