Artist’s impression of a relativistic jet of a gamma-ray burst (GRB), breaking out of a collapsing star, and emitting very-high-energy photons (DESY, Science communication Lab)
The DESY Research Centre has revealed an astonishing images of a cosmic event which occurred recently near the Earth. The center revealed that what it calls an “exceptional cosmic explosion” which challenges established theory of gamma-ray bursts in the universe.
A specialized observatory in Namibia recorded what is described as the most energetic radiation and longest gamma-ray afterglow of a so-called gamma-ray burst (GRB) to date. The center stated that observations made with the High Energy Stereoscopic System (H.E.S.S.) challenge the established idea of how gamma-rays are produced in these colossal stellar explosions which are the birth cries of black holes, as the international team reports in the journal Science.
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On 29 August 2019 the satellites Fermi and Swift detected a gamma-ray burst in the constellation of Eridanus. The event was catalogued as GRB 190829A according to its date of occurrence.
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“Gamma-ray bursts are bright X-ray and gamma-ray flashes observed in the sky, emitted by distant extragalactic sources,” explains DESY scientist Sylvia Zhu, one of the authors of the paper. “They are the biggest explosions in the universe and associated with the collapse of a rapidly rotating massive star to a black hole. A fraction of the liberated gravitational energy feeds the production of an ultrarelativistic blast wave. Their emission is divided into two distinct phases: an initial chaotic prompt phase lasting tens of seconds, followed by a long-lasting, smoothly fading afterglow phase.”
Artist’s impression (DESY communication Lab)
The comparatively short distance to this gamma-ray burst allowed detailed measurements of the afterglow’s spectrum, which is the distribution of “colors” or photon energies of the radiation, in the very-high energy range. “We could determine GRB 190829A’s spectrum up to an energy of 3.3 tera-electronvolts, that’s about a trillion times as energetic as the photons of visible light,” explains co-author Edna Ruiz-Velasco from the Max Planck Institute for Nuclear Physics in Heidelberg. “This is what’s so exceptional about this gamma-ray burst – it happened in our cosmic backyard where the very-high-energy photons were not absorbed in collisions with background light on their way to Earth, as it happens over larger distances in the cosmos.”
DESY is one of the world’s leading accelerator centers. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behavior of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe.
