First detection of very high energy gamma-ray bursts


The most violent cosmic explosions in the Universe give rise to gamma-ray bursts, very short yet highly energetic flashes of photons. Two of them have now exceeded the highest energy levels ever observed until now, confirming that these gamma-ray emissions can reach energy levels at least a trillion times higher than that of visible light. The observations provide, for the first time, evidence of the presence in gamma-ray bursts of particles accelerated to extreme energies. They also show that the particles still exist, or were created, a long time after the initial burst. The most likely hypothesis is that the initial explosion gives rise to the formation of a jet of plasma which, when it encounters the interstellar medium, slows down, creating a shockwave that acts as a kind of ‘cosmic particle accelerator’. The findings were obtained by international research teams1, involving in particular CNRS scientists through the participation of various observation instruments2, and are presented in three papers published in the journal Nature on November 20, 2019.

One of the very high energy gamma-ray bursts, as observed by the H.E.S.S telescope array. The red cross shows the position of the burst, determined from optical measurements.
© Abdalla et al./H.E.S.S. Collaboration


  • 1. In France, researchers worked in the Centre de physique des particules de Marseille (CNRS/Aix-Marseille Université), the Centre d'études nucléaires de Bordeaux Gradignan (CNRS/Université de Bordeaux), the Institut de planétologie et d'astrophysique de Grenoble (CNRS/Université Grenoble Alpes), the Institut de recherche sur les lois fondamentales de l'Univers (CEA), the laboratoire « Astroparticule et cosmologie » (CNRS/Université de Paris), the laboratoire « Astrophysique, interprétation, modélisation » (CNRS/CEA/Université de Paris), the Laboratoire d'Annecy de physique des particules (CNRS/Université de Savoie Mont Blanc), the Laboratoire de physique nucléaire et de hautes énergies (CNRS/Sorbonne Université), the laboratoire « Galaxies, étoiles, physique, instrumentation » (Observatoire de Paris - PSL/CNRS), the Laboratoire Leprince-Ringuet (CNRS/Ecole polytechnique), the Laboratoire Univers et particules de Montpellier (CNRS/Université de Montpellier) and the Laboratoire Univers et théories (Observatoire de Paris - PSL/CNRS).
  • 2. Including the H.E.S.S and MAGIC telescope arrays.

A very-high-energy component deep in the γ-ray burst afterglow. H.E.S.S. Collaboration, Abdalla et al. Nature, November 20, 2019.
Observation of inverse Compton emission from a long γ-ray burst. Veres et al. Nature, November 20, 2019.
Teraelectronvolt emission from the γ-ray burst GRB 190114C. MAGIC Collaboration, Acciari et al. Nature, November 20, 2019.


Mathieu Jacobé de Naurois
Chercheur CNRS en astronomie
François Maginiot
CNRS press officer