Astronomers spot mysterious cosmic explosion active for 27 days
What's the story
Astronomers have discovered an extraordinary gamma-ray burst (GRB), one that outshines all other cosmic explosions of its kind. The central engine of this particular GRB, dubbed GRB 220706A and detected on July 6, 2022, remained active for about 27 days. This is a whopping 20 days longer than the previous record-holder. The discovery was made by a team from the University of Birmingham in England and published on arXiv.
Unexplained phenomena
Mystery of GRB 220706A
GRB 220706A is particularly interesting because its central engine remains a mystery.
"In a nutshell, GRB 220706A is an extremely late X-ray flare. X-ray flaring is common following GRBs, but previously it has always come within the first few days after we detect the burst," said study team member Benjamin Gompertz from the University of Birmingham.
The late flaring suggests an active process, which is unprecedented in known cosmic explosions.
Speculations
Understanding GRBs and their classification
GRBs are some of the most powerful explosions in the universe, usually associated with a massive star's collapse into a black hole. This results in long-duration GRBs.
Short-duration ones are thought to occur when two neutron stars collide.
However, GRB 220706A is an ultra-long GRB, a rare cosmic event where its central engine remains active for longer. Its cause is still unknown, making it even more intriguing for scientists.
Magnetar hypothesis
Possible causes for the unusual late flaring
The team speculated that GRB 220706A could be powered by a magnetar, a neutron star with an incredibly strong magnetic field.
"Our supernova looks a lot like that one, so a magnetar might be present here," Gompertz said.
Another possibility is that the GRB jet and supernova are colliding with dense material ejected toward the end of the parent star's life. This could also explain its unusual brightness and late flaring.
Future prospects
Future missions to study ultra-long GRBs
The team plans to use newly launched missions like the Einstein Probe, which is more sensitive in X-rays than gamma rays, to find more ultra-long GRBs.
"With any luck, we'll get a few more of these to chase so that we can start trying to understand the incredible power sources that drive them," Gompertz concluded.
This discovery could open new avenues in our understanding of cosmic explosions and their underlying mechanisms.