Messages from earliest histories

Before 15 April 2020, scientists were still struggling to explain the nature of short gamma-ray bursts (GRB), having only known about their longer, two-second sidekicks. But on this day, the ability for scientists to explain other GRBs was upped tenfold.

Before then, all that was known about these cosmic phenomena was that they were traced to supernovas, or two neutron stars, spiralling into each other.

This may not seem relevant to anyone other than scientists enthralled with the stars, but GRBs have more of an effect on Earth than some can fathom.

They can disrupt cellphone reception, but for scientists the GRBs bring messages from the past, to the earliest histories of the universe.

Earth is blasted with GRBs on most days. Not all of these are significant, but they can produce the most powerful explosions in the universe.

The GRB in question, dubbed 200415A, was discovered to have come from a rare and powerful neutron star called a magnetar. It swept past Earth and came rather close – at least, in cosmic terms.

It exploded in galaxy NGC 253’s Sculptor constellation, 11.4 million light-years from us. “That is relatively close when talking about the nuclear frying power of a giant flare GRB,” researchers said.

Out of the thousands of neutron stars, only 30 are known to be magnetars.

A neutron star is a massive star that has died and exploded into a supernova. It is as large as a 20km valley, but just a spoonful of it would weight tons on earth, said University of Johannesburg astro-particle physics director Professor Soebur Razzaque.

What’s left of these majestic stars is what causes the biggest explosions in the universe.

Razzaque led a team predicting GRB behaviour, and their research was published in Nature Astronomy in January. They were trying to understand how stars end their life, and how GRBs are then produced.

What’s the big deal? Researchers struggle to find out where GRBs come from, only knowing that supernovas spout longer GRBs, which are busts lasting two seconds or more.

GRB200415A lasted 140 milliseconds, or as long as it takes to blink an eye. It was found careening past Mars, and was picked up by satellites, a spacecraft and the International Space station.

Razzaque said that magnetars are up to 1 000 times more magnetic than ordinary neutron stars. And they put our sun to shame, which is rather ordinary.

When a star like our sun dies, it gets bigger and becomes a red giant star. It then collapses into a smaller star called a white dwarf.