Astonishing energy of BOAT gamma rays revealed
Earlier this year, it was reported that the Earth was hit by the brightest gamma-ray bursts seen since the dawn of civilization. Now, a team of astronomers has assigned a value to the energy contained in those blasts and it's staggering to say the least.
The gamma-ray burst (GRB) reported in April of this year was actually confirmed by NASA as having struck Earth on October 9, 2022, and having originated about two billion light-years away. The space agency called the occurrence a "1-in-10,000-year event" and said that it was most likely caused by the creation of a black hole as a supermassive star collapsed inwards, releasing gamma rays from the shock waves produced by such a massive galactic event.
The burst is technically known as GRB 221009A, but has come to be known by the much more user-friendly name of the "Brightest of All Time," or BOAT.
Now, researchers at China's Large High Altitude Air Shower Observatory (LHAASO), a facility designed to detect gamma and cosmic rays, have put a figure to the energy contained in those gamma rays: 13 teraelectronvolts (TeV). They also say the celestial body that collapsed releasing all that energy was a star about 20 times larger than our Sun.
The final figure falls short of the 18 TeV predicted when the blast was first observed, but it's still a mighty amount of power. An electronvolt is a particular measure of the kinetic energy picked up by an electron as it accelerates in a vacuum under certain constraints. One teraelectronvolt equals 1012 electronvolts. Most GRBs wind up in the 0.5 TeV range. With its 13 TeVs, BOAT is strikingly more powerful and holds the record for the most energy witnessed on Earth in a GRB and the first detection of one over 10 TeVs.
In second place in the cosmic GRB competition is one likely caused by a neutron star collision, which was reported less than a month ago.
The fact that the LHAASO was able to measure so much energy from a GRB, says the research team, may point to the fact that intergalactic space might be more transparent than previously thought. The team plans to continue its research into BOAT, especially why the afterglow of the event lasted much longer than our current understanding of GRBs says it should have.
In the paper describing their measurement process in the journal Science Advances, the researchers give special thanks to the team involved in the work.
"We would like to thank all staff members who work at the LHAASO site 4400 m above sea level year-round to maintain the detector and keep the water recycling system, electricity power supply, and other components of the experiment operating smoothly," they wrote.
Update (Nov. 20, 2023): This article originally stated that "One teraelectronvolt equals 1,012 electronvolts". This was incorrect (by quite a bit). We sincerely apologize for the error, which has now been corrected, and thank everyone who pointed it out.