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Scientists have been buzzing ever since multiple space-based detectors captured a powerful gamma-ray burst (GRB) in October 2022. The burst was so energetic that astronomers Nicknamed Boat (The brightest ever.) Now, an international team of astronomers has analyzed the unusual energy peak detected by NASA’s Fermi Gamma-ray Space Telescope and concluded that it is an emission spectrum. New paper The researchers, published in the journal Science, say that this is the first reliable emission line to be identified in 50 years of GRB research.
As Previously reportedGamma-ray bursts are very high energy explosions that occur in distant galaxies for anywhere from a few milliseconds to a few hours. There are two types of gamma-ray bursts: most (70%) are long bursts that last more than 2 seconds and are accompanied by a bright afterglow. These are usually associated with galaxies with rapid star formation. Astronomers believe that long bursts are associated with the death of a massive star, where it collapses to form a neutron star or a black hole (or a newly formed galaxy). MagnetarBaby black holes produce jets of high-energy particles traveling close to the speed of light, with enough force to penetrate the remains of the protostar and emit X-rays and gamma rays.
Gamma-ray bursts lasting less than 2 seconds (about 30%) are considered short bursts, usually emanating from regions where there is little star formation. Astronomers believe that these gamma-ray bursts are the result of the merger of two neutron stars, or the merger of a neutron star and a black hole. This hypothesis is supported by: Confirmed in 2017 When the LIGO collaboration captured the gravitational wave signal of the merger of two neutron stars accompanied by a powerful gamma-ray burst associated with a kilonova.
Some papers Published Last year, we reported the results of our analysis of all the observational data, which showed that GRB 221009A is indeed BOAT, and that it appeared particularly bright because its narrow jet was pointing directly at Earth. But the various analyses also yielded some surprising results that have astronomers puzzled. Most notably, a supernova was supposed to occur a few weeks after the initial burst, but astronomers didn’t detect it – probably because it was so faint and thick dust clouds in that part of the sky were obscuring the incoming light.
Earlier this year, astronomers confirmed that BOAT came from a supernova, with evidence of major elements such as calcium and oxygen that are expected to be found in supernovae. However, they found no evidence of heavier elements such as platinum or gold, which relates to the long-standing question of the origin of such elements in the universe. BOAT may be special in that respect, but more data will tell us more.
“It gave me goosebumps.”
Minutes after BOAT exploded, Fermi’s Gamma-Ray Burst Monitor recorded an unusual energy peak, a feature that scientists now say is the first reliable emission line identified in 50 years of GRB research.
The newly detected spectral emission lines are likely the result of matter-antimatter collisions, producing gamma-ray pairs that are blue-shifted to higher energies as they observe jets, the authors say. Having a spectral emission associated with a GRB is important because it can shed light on the specific chemicals involved in the interaction. Previous studies have reported possible evidence of absorption or emission lines in other GRBs, but they have typically found that they are likely statistical noise.
This isn’t the case with this latest detection, said co-author Om Sharan Salafia of the INAF Brera Observatory in Milan, Italy. added The chance that this is a statistical fluctuation is “less than one in 500 million,” says co-author Maria Edvige Ravasio, a colleague at INAF. said When she first saw the traffic light, “I got goosebumps.”
Why did it take astronomers so long to discover it? When BOAT first exploded in 2022, most space-based gamma-ray detectors, including the Fermi Space Telescope, were saturated and unable to measure the most intense part of the explosion. The emission lines appeared about five minutes after the explosion, when it was dim enough for Fermi to measure. According to the authors, the spectral emission lasted for about 40 seconds and reached a peak energy of about 12 MeV, compared to 2 MeB or 3 MeB for visible light.
Science, 2024. DOI: 10.1126/science.adj3638 (About DOIs).
