Brightest space bursts reveal possible hints of dark matter

isn Sunday, October 9, Judith Rakusin 35,000 feet in the air, en route to a high-energy astrophysics conference, when the largest cosmic explosion in history occurred. “I landed, looked at my phone, and there were dozens of messages,” said Rakusin, an astrophysicist at NASA’s Goddard Space Flight Center in Maryland. “It was really exceptional.”

The explosion was a long gamma-ray burst, a cosmic event in which a massive dead star unleashes a powerful jet of energy as it collapses into a black hole or neutron star. This particular burst was so bright that it overwhelmed the Fermi Gamma-ray Space Telescope, an orbiting NASA telescope designed to observe such events. “There were so many photons per second that they couldn’t keep up,” said Andrew Levan, an astrophysicist at Radboud University in the Netherlands. Even the explosion appears to have damaged Earth’s ionosphere, the upper layer of Earth’s atmosphere. swelling in size “It’s pretty incredible that you can change the Earth’s ionosphere from an object halfway across the universe for a few hours,” says Doug WelchAn astronomer at McMaster University in Canada.

Astronomers called it BOOT – “brightest ever” – and began to scour it for information about gamma-ray bursts and the cosmos more generally. “Even 10 years from now there will be new understanding from this data set,” said Eric Burns, an astrophysicist at Louisiana State University. “It still hasn’t quite hit me that this really happened.”

Preliminary analysis suggests that there are two reasons why the boat is so bright. First, it happened about 2.4 billion light-years from Earth – fairly close to the gamma-ray burst (although outside our galaxy). It is also possible that BOAT’s powerful jet was directed at us. Two factors combine to create such an event that only happens once every few hundred years.

Perhaps the most fruitful observation occurred in China. There, in Sichuan province, the Large High Altitude Air Shower Observatory (LHASO) tracks high-energy particles from space. In the history of gamma-ray burst astronomy, researchers have observed only a few hundred high-energy photons coming from these objects. LHAASO 5,000 views From this one event. “The gamma-ray burst basically went straight up into the sky above them,” said Sylvia Zhuis an astrophysicist at the German Electron Synchrotron (DESY) in Hamburg.

Among these detections was a suspected high-energy photon at 18 teraelectron volts (TeV) – four times more powerful than anything seen before in gamma-ray bursts and more powerful than the maximum energy achievable by the Large Hadron Collider. Such a high-energy photon should have been lost on its way to Earth, absorbed by interactions with the background light of the Universe.

So how did it get here? one possibility That is, after the gamma-ray burst, a high-energy photon was transformed into an axon-like particle. axions Assuming lightweight particles that Can explain dark matters; Particles like axions are thought to be slightly heavier. can be high-energy photons are converted into such particles by strong magnetic fields, such as around a rotating star. The axon-like particle would then travel unhindered across the vastness of space. As it arrives in our galaxy, magnetic fields will transform it into a photon, which will then make its way to Earth.

In the weeks following the initial detection, multiple teams of astrophysicists This process is recommended In papers uploaded to the scientific preprint site arxiv.org. “It would be a very incredible discovery,” said Giorgio Galanti, an astrophysicist at Italy’s National Institute for Astrophysics (INAF). This paper is the first.

Yet other researchers think that the detection of LHAASO may be a case of mistaken identity. Perhaps the high-energy photon came from somewhere else, and its precise arrival time was just a coincidence. “I’m very skeptical,” he said Milena Kronogorcevic, an astrophysicist at the University of Maryland. “I’m currently leaning towards this being a background event.” (To complicate matters further, a Russian observatory Report A hit by an even higher-energy 251 TeV photon coming from the explosion. But “the jury is still out,” said Rakusin, deputy project scientist for the Fermi telescope. “I’m a little skeptical.”)

So far the LHAASO team has not published detailed results of their observations. Barnes, who is coordinating a global collaboration to study BOAT, hopes they do. “I’m very curious to see what they have,” he said. But he understands why a little caution might be necessary. “If I were sitting on data that had a few percent chance of defining evidence of dark matter, I would be extraordinarily cautious right now,” Barnes said. If the photon can be attached to BOAT, “it will likely be evidence of new physics and possible dark matter,” Kronogorchevic said. The LHAASO team did not respond to requests for comment.

Even without data from LHAASO, the amount of light seen from the event could enable scientists to answer some big questions about gamma-ray bursts, including big puzzles about jets. “How is the jet launched? What happens to the jet as it spreads out into space?” says Tyler Persotan, an astrophysicist at Goddard. “These are really big questions.”

Other astrophysicists hope to use BOAT to determine why only some stars undergo gamma-ray bursts when they go supernova. “It’s a big mystery,” he said yvette cedes, an astronomer at the Harvard-Smithsonian Center for Astrophysics. “It must be a very large star. A galaxy like ours will probably emit a gamma-ray burst every million years. Why is there such a rare population of gamma-ray bursts?

Whether gamma-ray bursts produce a black hole or a neutron star at the core of a collapsed star is also an open question. Preliminary analysis of the boat reveals that the former incident has occurred in this case. “The jet has so much energy it basically has to be a black hole,” Barnes said.

What is certain is that this is a cosmic event that will not be accepted for many, many lifetimes. “We’re all going to die before we get a chance to do it again,” Barnes said.

Lead image: The rings around the explosion, seen here in color data from NASA’s Swift Observatory, are formed when X-rays scatter hidden dust in our Milky Way galaxy. Credit: NASA Swift Observatory; Processing: John Miller.

This article was Originally published above Quanta abstraction Blog.