One of the most powerful ever detected: Astronomers determine the source of a rare massive burst of gamma rays

One of the most powerful ever detected: Astronomers determine the source of a rare massive burst of gamma rays

Gamma Ray Burst

Artist’s impression of a gamma-ray burst just after the collapse of its progenitor star. Credit: Nuria Jordana-Mitjans/University of Bath

Scientists determine that a gamma-ray burst detected on Earth was caused by a space explosion that occurred less than 900 million years ago.

On September 5, 2021, light from a Highly Energetic Gamma Burst (GRB) – an incredibly energetic explosion that occurred in a distant galaxy – reached our planet. To arrive on Earth, it traveled for more than 12.8 billion years. The glow began its journey when the Universe (which is believed to be 13.7 billion years old) was only 880 million years old.

A worldwide team of astronomers studied the afterglow of the explosion in the months following this discovery in order to understand the cause. Dr Andrea Rossi, a researcher at the Italian National Institute of Astrophysics (INAF), led the group. Professor Carole Mundell from the University of Bath was also involved.

The scientists came to the conclusion that the GRB that caused the glow was one of the most distant and most energetic ever found. Plus, it had one of the brightest afterglows ever seen.

Scientists were also surprised to see that despite GRB 210905A’s age, it exhibited properties (such as X-ray wavelength) that are strikingly similar to those observed in GRBs produced by cosmic explosions that occur. are produced both much more recently and much closer to Earth.

“Thanks to our observations, we can conclude that the mechanism responsible for GRBs does not evolve with the Universe”, explains Dr Rossi.

Professor Mundell, Hiroko Sherwin Professor of Extragalactic Astronomy and Head of Astrophysics at Bath, was also involved in the research. She says: “As one of the most powerful and distant cosmic explosions ever discovered, this rare gamma-ray burst joins a small club of such explosions discovered early in the history of the Universe – and the one This is from the brightest host galaxy ever. detected.

“This discovery gives us a new understanding and confirmation that massive stars – which live fast and die hard – form and evolve early in the universe.”

First came the explosion

The GRB observed in this study was of the “long” type, i.e. it came from a

black hole
A black hole is a place in space where the gravitational field is so strong that not even light can escape. Astronomers classify black holes into three categories based on their size: miniature, stellar, and supermassive black holes. Miniature black holes could have a mass less than that of our Sun and supermassive black holes could have a mass equivalent to billions of our Sun.

” data-gt-translate-attributes=”[{” attribute=””>black hole that would have arisen from the catastrophic collapse of a massive star. ‘Short’ GRBs are usually linked to the collision of compact objects such as neutron stars.

The light burst was first detected by instruments aboard the Neil Gehrels Swift Observatory in orbit around the Earth, as well as Konus-WIND, a GRB-hunting telescope operating in interplanetary space.

Observations continued for eight further months using an array of major telescopes both on the ground and in space. These included the Hubble, Swift, and Chandra telescopes.

“Once again, we have shown that when dealing with transient phenomena, you need to be able to act quickly and have the right tools,” says Dr. Rossi. “You have to be able to both observe the phenomenon when it is still bright to obtain a clear and unequivocal result, and then you need access to those facilities that allow you to cover a large wavelength range, from gamma-rays to X-rays, optical and radio.”

The researchers expect to deepen their understanding of the original explosion with the help of the recently launched

“This telescope has just begun to demonstrate its incredible capabilities, promising to unveil the characteristics of the environment where the massive star at the origin of this GRB was born,” says Dr. Rossi.

Most of the astronomers involved in the GRB study are members of the STARGATE collaboration, which brings together all those active in GRB follow-up with


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