Will the strongest gamma-ray burst reveal these supernova "explosive materials"?

"We are in awe and feel very lucky to be able to study it"

Figure 1 Observation of GRB221009A by the Gemini South Telescope in Chile

(Image credit: Gemini Observatory/NOIRLab/NSF/AURA//B. O'Connor (UMD/GWU)

& J. Rastinejad & W. Fong (Northwestern University)

On October 9, 2022, a bright light passed by our planet, even temporarily blinding several satellite detectors, and all eyes were focused on the super-powerful gamma-ray burst that lit up the sky. Gamma rays are the most energetic type of explosion known in the universe besides the Big Bang, and their appearance is often a sign of the birth of a black hole.

In just a few hours, tens of thousands of telescopes around the world pointed to the source of the explosion, recording this historic moment. This event has a nickname called "BOAT" (brightest of all time), and its official name is "GRB221009A". Scientists hope to use it to shed light on the physics of terrifying black holes. Brandon O'Connor of Maryland and George Washington University said: "This is a once-in-a-century, even once-in-a-millennium event. We are amazed by its appearance and very fortunate to have the opportunity to study it."

In fact, gamma rays are not rare. Almost every day, a beam of them passes by the Earth, and they appear even more frequently in the universe. Neutron stars are produced in the supernova explosion of massive stars. This stellar corpse gradually burns out its energy, and the gamma rays caused by the collapse only flash for a fraction of a second. Gamma rays caused by black holes can last for several minutes. They are produced from supernova explosions, swallowing up a large amount of matter from the parent star and being ejected in the form of huge jets.

The gamma-ray burst observed this time was particularly outstanding compared to previous ones, producing photons that bombarded the detector for ten minutes and carried much more energy than usually observed. At 18 teraelectronvolts, the photons of GRB221009A have twice the energy of photons produced by the Large Hadron Collider, the most powerful particle generator on Earth. The afterglow of the explosion, produced by the interaction of gamma rays with cosmic dust, was also unusual. Although the gamma-ray source was blocked by a thick band of the Milky Way, it was brighter than the afterglow seen before. The explosion ionized the Earth's atmosphere, interfering with long-wave radio communications.

Figure 2 GRB221009A gamma-ray burst observed by the Gemini South Telescope in Chile

(Image credit: Gemini Observatory/NOIRLab/NSF/AURA//B. O'Connor (UMD/GWU)

& J. Rastinejad & W. Fong (Northwestern University)

Brandon O'Connor said that on October 14, 2022, five days after the gamma-ray emission, we used the Gemini South Telescope in Chile to track down the source of about 30% of the gamma rays, which came from the dusty Sagittarius galaxy, also known as the Arrow Galaxy. It also brought another surprise. This gamma-ray burst is closer to the earth than before.

"The radiation is produced by the collapse of massive stars, which have very short life spans," said Jillian Rastinejad, a student at Northwestern University who participated in the measurement. "They follow the history of star formation in the universe, so the more intense the star formation, the more numerous these bursts are, which is about half the age of the universe. However, this gamma-ray burst occurred later and closer to us."

Astronomers speculate that GRB221009A originated from 2.4 billion light-years away from Earth. They have observed gamma-ray bursts at closer distances before, but this one stands out due to its high energy. "It is because it is bright enough that we have ample time to dig out more details," said Brandon O'Connor. "There are currently at least 50 telescopes observing at full wavelengths, and we can make the most of scientific technology."

In fact, the ray burst only lasts for a few minutes, but the aftermath can last for weeks. In addition, scientists are also working to find explosions caused by supernovae, which eject matter outward at a slower speed. Brandon O'Connor said that our current understanding is that massive stars collapse inward to form black holes, and the debris of the stars is constantly sucked in and ejected from the black hole in the form of jets, running at nearly the speed of light, forming gamma-ray bursts. At the same time, part of the debris bounces outward and runs at a slower speed, forming a supernova explosion.

Figure 3 Cosmic dust ring ignited by the strongest gamma-ray burst

(Image credit: NASA/Swift/A. Beardmore (University of Leicester, UK))

The initial gamma-ray burst interacted with the surrounding matter to form an aftermath. Rastinejad said that this wavelength spans the range of electromagnetic waves and is best observed in the X-ray and radio wave regions. Scientists are still working to observe the ray aftermath. It was first photographed by NASA's gamma-ray tracking satellite Swift, forming a colorful ring around the source a few hours after the explosion.

Telescopes can now see the first signs of a supernova explosion at GRB221009A. Rastinejad pointed out that the explosion will be fully presented to us in the next few weeks, but due to the limited location of the explosion source, we may not be able to see the entire supernova explosion and demise. It gradually goes behind the sun, so it will last until the end of November this year, and we can observe it again in February next year.

She pointed out that in 2023, NASA's James Webb and Hubble Space Telescopes will join the work, contributing their superb optical and infrared detection capabilities respectively. Exploring the energy produced by the explosion is a landmark event, as is exploring the chemicals involved. We still don't know how some heavy elements in the universe are produced, and studying supernovae can help us solve the mystery.

Figure 4 Newborn black holes form powerful gamma-ray jets

(Image credit: NASA/ESA/M. Kornmesser)

Gamma rays were discovered accidentally in the 1960s by military satellites used to spy on Soviet nuclear tests. They remained a mystery for decades until the 1990s, when scientists first realized that gamma rays hidden throughout the universe might be related to the collapse of stars.

At present, a lot of understanding about gamma rays is still based on theoretical calculations and simulations. Scientists believe that this gamma-ray burst will well revise previous theories. Scientists will make full use of this once-in-a-lifetime opportunity, and a large number of articles will be published in the next few months.

Although explosions of similar energy are a boon to science, scientists don't want them to happen near Earth, or even in our galaxy. Scientists think gamma rays beaming toward Earth from thousands of light-years away could damage the ozone layer, trigger atmospheric changes that eventually lead to ice ages. In fact, a similar gamma-ray burst caused one of the five largest mass extinction events on Earth, the Ordovician mass extinction about 440 million years ago.

"Fortunately, the gamma-ray burst produced by this jet is very narrow, only a few degrees wide," said Brandon O'Connor. "If it happened to occur in our galaxy and pointed directly at us, it would be dangerous, but fortunately the probability of such a phenomenon occurring is extremely low."

Additional explanation: ① NOIRLab: National Optical-Infrared Astronomy Research Laboratory

National Optical-Infrared Astronomy Research Laboratory

② NSF: National Science Foundation

③ AURA: Association of Universities for Research in Astronomy

Universities Astronomy Research Association

④ Teraelectronvolt, also known as teraelectronvolt, 10^12 ev

⑤ LHC: Large Hadron Collider

⑥ Swift: Swift Gamma-ray Burst Explorer

BY: Tereza Pultarova

FY: gxm

If there is any infringement of related content, please contact the author to delete it after the work is published.

Please obtain authorization for reprinting, and pay attention to maintaining integrity and indicating the source