Bursting at the extremes

BY RACHEL RAYNER (CSIRO)

When a one in 10,000 year event flooded gammaray detectors in space, telescopes around the world were asked to point at the source. CSIRO’s radio telescope ASKAP, an SKA precursor, was no exception.

The event was a gamma-ray burst: one of the biggest known explosions in the Universe. Detailed findings about the burst have been published in The Astrophysical Journal Letters It is thought bursts of gamma radiation and x-rays erupt during the death throes of enormous stars collapsing into black holes. One has never been detected in our own galaxy, which is good: it has been predicted that such an enormous explosion close to Earth could blow our atmosphere away!

This bright burst offered the perfect opportunity to test current models on what happens during a star’s demise. This is when material is being expelled from the star at almost the speed of light as it collapses into a black hole. It is important that telescopes of all wavelengths quickly conduct observations to understand more about these extreme events.

XMM-Newton images recorded 20 dust rings, 19 of which are shown here in arbitrary colours. The image merges observations made two and five days after GRB 221009A erupted. Dark stripes indicate gaps between the detectors. GRB221009A is only the seventh gamma-ray burst to display X-ray rings, and it triples the number previously seen around one.

Credit: ESA/XMM-Newton/M. Rigoselli (INAF)

Australian astronomers observed the cosmic event’s radio wave signature with ASKAP. The radio waves are produced by shockwaves from the highly energetic ejected material ploughing into the surrounding matter. Observations from ASKAP, combined with data from other telescopes, such as the XMM-Newton space observatory which looks for x-rays, showed that they are difficult to explain within current theoretical models of gamma ray burst events.

A brightening supernova was expected to occur a few weeks after the initial event. However, none has yet been detected, showing that the Universe still has plenty of mysteries for us to uncover.

Read the paper: https://iopscience.iop.org/collections/apjl-230323-172_Focus-on-the-Ultra-luminous-GRB-221009A

The radio follow up observations are detailed here: https://arxiv.org/abs/2303.13583

BELOW: This NASA graphic depicts the different types of light emitted following a gamma ray burst.

Credit: NASA’s Goddard Space Flight Center.