2023-10-15 20:09:50
Scientists from the High Energy Stereoscopic System in Namibia (HESS) discover the highest energy gamma rays ever emitted by a pulsar (a piece of a dead star with a high magnetic field), capable of reaching 20 teraelectronvolts of photons: about ten thousand millions of times the energy of visible light.
“These dead stars are composed almost entirely of neutrons and are incredibly dense: a teaspoon of their material has a mass of more than five billion tons, or about 900 times the mass of the Great Pyramid of Giza,” explains HESS scientist Emma de Oña Wilhelmi, co-author of the publication who works at the German Electron Synchrotron (DESY), according to ‘Europa Press’.
This finding is difficult to reconcile with the theory of the production of pulsating gamma rays, according to the journal ‘Nature Astronomy’. The discovery of this extraordinary energy has been detected in the Vela pulsar, in the constellation also called Vela.
The result of the research “challenges our previous knowledge of pulsars” while requiring “a rethinking of how these natural accelerators work,” explains research director Arache Djannati-Atai, from the Astroparticle & Cosmology (APC) laboratory. in France. “The traditional scheme according to which particles accelerate along magnetic field lines inside or slightly outside the magnetosphere cannot sufficiently explain our observations,” he adds.
Discovery in the Vela pulsar
To start, what are pulsars? They are remains of a star that explodes spectacularly with a supernova, leaving tiny remains of the dead star, about 20 kilometers in diameter, which rotate at high speed and have an enormous magnetic field.
The Vela pulsar, so named because it resembles a ship’s sail, is the brightest pulsar in the radio band of the electromagnetic spectrum and the brightest persistent source of cosmic gamma rays in the gigaelectronvolt (GeV) range. . It is capable of rotating about eleven times per second. “However, above a few GeV, its radiation ends abruptly, presumably because the electrons reach the end of the pulsar’s magnetosphere and escape from it,” reports the aforementioned news agency.
Scientists have discovered a new radiation component at even higher energies, up to tens of teraelectronvolts (TeV). This is revealed by Christo Venter, co-author of the study and professor at Northwestern University in South Africa.
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