February 5, 2023

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Science has detected, from the merger of two stars, high-energy gamma-ray bursts

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outside our galaxy, a billion years ago 2 neutron stars They danced around each other until they merged and dispersed A long signal of gamma energy has never been seen before. A reconstruction of what happened was provided by A The research team is led by the Gran Sasso Science Institute (Gssi) in L’Aquila. The path that led to the discovery began, about a year ago, with Observatory’s Neil Gehrels Express Satellite in which a gamma ray burst was observed. The signal is labeled with the term “gamma ray burst” (Grb), baptized by name Grb211211A. It is one of the strongest flashes of this force that attracts the most attention of the international scientific community. We start examining Grb211211A and surprises right away. The prolonged emission of gamma rays, usually associated with explosions of massive stars (supernovae), is instead followed by visible light (kilonova) similar to that observed in Gw170817: the merger of two neutron stars giving rise to 1 of the first gravity. Taken 5 years ago. This phenomenon subsequently also generates a high-energy gamma-ray emission, which began several minutes after the Swift satellite was observed and lasted a few hours. catches her Fermi space satellite with on board Large area telescope instrumentDeveloped with inputNational Institute of Nuclear Physics at L’Aquila Science Laboratories, the telescope aims its powerful eyes at Grb211211A, and it was the Gssi researchers who observed and studied the phenomenon. “The Grb211211A event showed a high-energy gamma-ray light flux several minutes after the two neutron stars merged and lasted several hours.” he said that Alessio Melinked Infn Confirming that the late emission of the GRB, in physics is called ‘twilight’Weakened over time, but the flow held steady for a long time. “While the afterglow’s emission is explained by a super-relativistic jet, consisting of particles traveling near the speed of light, interacting with the interstellar medium, what we were observing had never been seen before and was impossible to explain by jet. We had to find a new source of the emissions.” Biswajit Banerjee, Gssi postdoctoral fellow. The tipping point came from the visible light, kilonova. The excess of high-energy gamma rays would be the result of the interaction between electrons accelerating in a relativistic jet that follows the super-relativistic jet and light from the kilonova itself. “Photons obtain energy from electrons in a process called inverse Compton scattering by converting it into gamma rays,” he explains. Gore Oganesian, Gssi Researcher. Among the many questions raised by GRB211211A, it will be necessary to investigate how the merger of two neutron stars, which were thought to only give rise to short-lived GRBs, could also produce long-lived emissions of gamma rays as in this case. A discovery that opens fascinating new scenarios in astronomy for Marica Branchesi, professor at Gssi associated with the Gran Sasso National Institute for Nuclear Physics.

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