Major scientific breakthrough announced, and South Africa played its part

TANYA FARBER

A whole new era in astrophysics has begun, and a South African team has been part of it.

WAVE DETECTOR: Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory to detect cosmic gravitational waves. It is located in Livingston, Louisiana, and Hanford, Washington, USAPicture: WITS UNIVERSITY

Two massive neutron stars did what they’ve always done – albeit once every million years: collided and merged so spectacularly that the same amount of energy as three times the mass of the sun was emitted.

But now, for the first time in history, human beings on a little speck called Planet Earth were able to witness it because their telescopes – thousands of kilometres apart – were able to point in that direction together and locate exactly where it was happening and also what was happening.

This is a major scientific breakthrough.

Not only was the event detected by two separate instruments measuring gravitational waves generated by the event, but telescopes were also able to record the light from it.

According to Irish astronomers who were part of the international team, the observation is “hugely important” because it has enabled scientists for the first time ever to prove where some of our heavy metals come from.

Gold and platinum, for example, formed by such nuclear reactions, are thrown out into space.

The South African team at the University of the Witwatersrand who worked with masses of data, were part of the international team that was able to alert other astronomers around the world as to what signals to look for so that their telescopes could pick it up too.

Two seconds later, a gamma-ray burst in the same part of the sky and was also observed by Professor Sergio Colafrancesco and his team from the School of Physics at Wits worked with data from their telescope system in Namibia (the HESS), and an Italian satellite (the AGILE).

This ushers in a whole new era of astronomical evidence that the scientists are calling “multi-messenger astrophysics”.

Colafrancesco describes it as, “Various techniques such as the gravitational wave laser interferometers – which is a displacement measuring tool – and astronomical techniques such as telescopes sensitive to electromagnetic radiation [being] used together to study one single event.”

A neutron star is not as compact as a black hole, but their merger might result in a black hole, according to a statement released by Wits University, and this particular event took place “between 1.1 billion and 2.2 billion light-years away from Earth”.

It was announced at an international media conference in Washington DC on Monday.

Scientists from over 70 observatories involved in the observation gathered large amounts of valuable data from the event, including learning what the source of the gravitational waves was.

“This is the first time ever that an astronomical event such as a gamma-ray burst, and other relative electromagnetic signals, was observed alongside an event large enough to emit gravitational waves,” says Colafrancesco.

These two neutron stars had a respective mass of 31 and 25 times the mass of the sun.

The resulting single start has a mass of 53 times that of the sun.

“We now know for certain that an event associated with gravitational waves is related to the emission of electromagnetic radiation, as in a gamma-ray burst,” says Colafrancesco.

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