2023-11-17 13:40:04
Aerial image of LHAASO observatory – XINHUA/JIN LIWANG
MADRID, 17 Nov. (EUROPA PRESS) –
Energy spectrum of brightest gamma-ray burst (GRB) observed to date challenges standard radiation model for this kind of cosmic explosions.
GRBs are immensely energetic explosions that have been observed in distant galaxies. They are the most energetic and luminous electromagnetic events since the Big Bang.
Recorded on Earth in October 2022GRB 221009A was initiated by the collapse of a massive star, which is more than 20 times heavier than the Sun when its nuclear fuel ran out.
The LHAASO (Large High Altitude Air Shower Observatory) observatory of the Institute of High Energy Physics of the Chinese Academy of Sciences recorded photons from GRB 221009A with energies greater than 10 TeVwhich was considered a milestone in the six-decade history of GRB research.
In the standard GRB model, residual radiation originates from the collision of explosion relics, traveling at nearly the speed of light, with the surrounding gas. This causes high-speed shock waves that accelerate the electrons to very high energies. These electrons then further scatter the surrounding photons to become high-energy gamma rays. In theory, the intensity of this radiation decreases rapidly as the energy of the photons increases.
However, LHAASO did not observe such a rapid drop in photon flux even at energies up to 13 TeV. This poses a challenge to the standard model GRB and hints that photons of around 10 TeV could be produced through more complex particle acceleration processes or new radiation mechanisms, according to a new study published in Science Advances by researchers at this observatory.
Furthermore, the energy spectrum measured by LHAASO challenges the standard radiation model of GRB afterglows, revealing that the intensity of cosmic background light in the infrared band is lower than expected. According to the study, this prompts a reassessment of the formation and evolution of galaxies in the universe, informa Xinhua.
Additionally, the new findings provide crucial information for examining Einstein’s theory of special relativity and new physics, such as exploring axions as candidate dark matter particles.
Located on a mountain about 4,410 meters above sea level in southwest China’s Sichuan Province and covering an area of 1.36 square kilometers, LHAASO is used to conduct cosmic ray observations and research. It is the world’s most sensitive ultra-high energy gamma ray detection device, with a large field of view and all-weather monitoring capability, covering two-thirds of the sky every day.
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