‘Extremely brutal’ gamma-ray bursts hit Earth

An extremely bright burst of gamma rays hits Earth. Now it turns out that such an event only happens once every 10,000 years.

Baton Rouge – When a bright, prolonged pulse of high-energy radiation hit Earth last fall, astronomers around the world were instantly dazzled. The radiation came from a gamma ray burst, the most powerful class of explosions in the solar system. In a matter of seconds, such an explosion can release as much radiation as our Sun in its lifetime.

And the gamma-ray burst on October 9, 2022 was brutal, as researchers suspected shortly after the explosion. Named GRB 221009A, the complex event quickly earned the nickname “BOAT,” short for “brightest of all time.” The astronomers weren’t doing it wrong, as more research into the celestial event is now showing.

The brightest gamma-ray burst since the beginning of human civilization

“GRB 221009A may have been the brightest X-ray and gamma-ray burst that has occurred since the dawn of human civilization,” said Eric Burns of Louisiana State University in Baton Rouge. communication. An assistant professor of physics and astronomy led an analysis of more than 7,000 gamma-ray bursts to find out how often such bright bursts occur. Answer: There is only a similar eruption every 10,000 years.

GRB 221009A may have been the brightest X-ray and gamma-ray burst that has occurred since the dawn of human civilization.

In fact, the October 2022 gamma-ray burst was so bright that it blinded most gamma-ray instruments in space, preventing them from directly recording the true intensity of the radiation. However, together with researchers from China and Russia, scientists from the United States have succeeded in reconstructing and analyzing the outbreak. The gamma-ray burst was 70 times brighter than anything previously observed. “It’s just a very brutal outbreak. We’ve never seen anything remotely like it,” Burns said at a news conference.

Gamma-ray burst fall 2022: The signal has been on its way for 1.9 billion years

Data from the NICER X-ray telescope on the International Space Station ISS as well as data from NASA’s old Voyager 1 space probe in interstellar space were used to analyze the explosion. Several studies on this topic are combined into one Focus topic of the specialized journal Astrophysical Journal Letters published.

The researchers calculated that the signal from GRB 221009A traveled through space 1.9 billion years before it reached Earth. Astronomers believe it is the “birth cry” of a black hole that formed when the core of a massive star collapsed under its own weight. The newly formed black hole quickly sucks in the matter surrounding it and shoots jets of matter (the so-called jets) into space in opposite directions. The particles inside are accelerated to near the speed of light, and the jets emit X-rays and gamma rays as they race through space.

A gamma-ray burst was directed directly at Earth

In reality, the jets weren’t unusually powerful, but one was pointed straight at the ground, explains Kate Alexander of the University of Arizona in Tucson. The more you look at the plane from the front, the brighter it appears. “Because this explosion was so close and so bright, it gave us an unprecedented opportunity to collect observations of afterglows across the electromagnetic spectrum and test how well our models represent what’s really going on in the GRBs,” Alexander continues. Alexander knows that for 25 years, models of gamma ray burst afterglows have been doing exceptionally well. “But they can’t fully explain this plane.”

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And one more thing is on the minds of the researchers involved: In the event of a gamma-ray burst like the one that occurred in October 2022, astronomy would expect a bright supernova weeks later — but that hasn’t been seen yet. “We can’t say with certainty that there was a supernova, which is surprising given the magnitude of the explosion,” explains astrophysicist Andrew Levan (Radboud University Nijmegen, Netherlands).

Both the James Webb Space Telescope and Hubble have been used to find the supernova. “When it’s there, it’s very weak. We plan to continue searching. However, it’s also possible that the entire star collapsed directly into the black hole instead of exploding. Further observations with the two space telescopes are planned. (Unpaid bill)