GHISELLINI, GabrieleGabrieleGHISELLINIGHIRLANDA, GiancarloGiancarloGHIRLANDAOganesyan, G.G.OganesyanASCENZI, STEFANOSTEFANOASCENZINava, LaraLaraNavaCelotti, A.A.CelottiSalafia, Om SharanOm SharanSalafiaRavasio, M. E.M. E.RavasioRonchi, M.M.Ronchi2022-03-212022-03-2120200004-6361http://hdl.handle.net/20.500.12386/31747We discuss the new surprising observational results that indicate quite convincingly that the prompt emission of gamma-ray bursts (GRBs) is due to synchrotron radiation produced by a particle distribution that has a low-energy cut-off. The evidence of this is provided by the low-energy part of the spectrum of the prompt emission, which shows the characteristic F<SUB>ν</SUB> ∝ ν<SUP>1/3</SUP> shape followed by F<SUB>ν</SUB> ∝ ν<SUP>-1/2</SUP> up to the peak frequency. This implies that although the emitting particles are in fast cooling, they do not cool completely. This poses a severe challenge to the basic ideas about how and where the emission is produced, because the incomplete cooling requires a small value of the magnetic field to limit synchrotron cooling, and a large emitting region to limit the self-Compton cooling, even considering Klein-Nishina scattering effects. Some new and fundamental ingredient is required for understanding the GRBs prompt emission. We propose proton-synchrotron as a promising mechanism to solve the incomplete cooling puzzle.STAMPAenArticle10.1051/0004-6361/2019372442-s2.0-85084393104https://www.aanda.org/articles/aa/full_html/2020/04/aa37244-19/aa37244-19.htmlhttp://arxiv.org/abs/1912.02185v22020A&A...636A..82GFIS/05 - ASTRONOMIA E ASTROFISICAPE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation