A huge explosion in space lasted for 27 days. Astronomers don’t know why
Astronomers have been left puzzled after discovering a record-breaking cosmic explosion that lasted for 27 days.
Researchers at the University of Birmingham said the massive gamma-ray burst (GRB), designated GRB 220706A, remained active for 20 days longer than any previous GRB ever recorded.
GRBs are the most powerful explosions in the universe, releasing more energy in a few seconds than our Sun will emit it is entire lifespan.
They can be caused by a massive star running out of fuel and collapsing into a black hole, and are typically short-lived, lasting from a few milliseconds to several minutes.
The central power source usually exhausts itself quickly, however a rare type of ultra-long GRB can continue to churn out high-energy flares for longer.
"The fact that we see flaring at around 27 days in the GRB's rest frame tells us that there's an ongoing active process, and that's unprecedented in the known population," Benjamin Gompertz from the School of Physics and Astronomy at the University of Birmingham told Space.com.
"The previous record for delayed flaring was about six days after the GRB."
Powerful gamma ray bursts can occur when a massive star collapses into a black hole
One possibility is that the star involved is much bigger than any previously observed in such events.
Dr Gompertz theorised that GRB 220706A may have required a type of star known as a blue supergiant, which is 1,000 times the radius of the Sun.
"We don't know what the central engine driving this outburst is, and that's what makes this such a compelling event," Dr Gompertz said.
"The fact that we see a supernova tells us that a star has collapsed, which is the standard power source for GRBs, but it doesn't immediately account for the extremely late flaring or unusually bright supernova. We can interpret that through previous events to some degree."
Gamma-ray bursts (GRBs) are mostly associated with the explosion of stars that collapse into black holes. In the explosion, two jets of very fast-moving material are ejected, as depicted in this artist's illustration (ESO/A Roquette)
The researchers hope future observations of ultra-long GRBs will help further their understanding of the cosmic phenomena.
The Einstein Probe, launched in 2024, could be a crucial instrument in assisting these efforts, with the X-ray space telescope capable of tracking such events that were previously impossible to observe.
The latest findings were published in a study titled 'An off-nuclear tidal disruption event discovered at late times: the case of TDE 2023mfm'.
