AGILE and Konus-Wind Observations of GRB 190114C: The Remarkable Prompt and Early Afterglow Phases

URSI, ALESSANDROALESSANDROURSI0000-0002-7253-9721TAVANI, MARCOMARCOTAVANI0000-0003-2893-1459Frederiks, D. D.D. D.FrederiksRomani, M.M.RomaniVERRECCHIA, FrancescoFrancescoVERRECCHIA0000-0003-3455-5082MARISALDI, MARTINOMARTINOMARISALDI0000-0002-4000-3789Aptekar, R. L.R. L.AptekarANTONELLI, Lucio AngeloLucio AngeloANTONELLI0000-0002-5037-9034ARGAN, ANDREAANDREAARGAN0000-0002-6230-665XBULGARELLI, ANDREAANDREABULGARELLI0000-0001-6347-0649Barbiellini, G.G.BarbielliniCARAVEO, PATRIZIAPATRIZIACARAVEO0000-0003-2478-8018CARDILLO , MARTINAMARTINACARDILLO0000-0001-8877-3996CASENTINI, CLAUDIOCLAUDIOCASENTINI0000-0001-8100-0579Cattaneo, P. W.P. W.CattaneoChen, A.A.ChenCOSTA, ELIAELIACOSTA0000-0002-9991-2709Donnarumma, I.I.DonnarummaEVANGELISTA, YURIYURIEVANGELISTA0000-0001-6096-6710FEROCI, MARCOMARCOFEROCI0000-0002-7617-3421Ferrari, A.A.FerrariFUSCHINO, FABIOFABIOFUSCHINO0000-0003-2139-3299Galli, M.M.GalliGIULIANI, ANDREAANDREAGIULIANI0000-0002-4315-1699LABANTI, CLAUDIOCLAUDIOLABANTI0000-0002-5086-3619LAZZAROTTO, FRANCESCOFRANCESCOLAZZAROTTO0000-0003-4871-4072Longo, F.F.LongoLUCARELLI, FabrizioFabrizioLUCARELLI0000-0002-6311-764XMorselli, A.A.MorselliPaoletti, F.F.PaolettiPARMIGGIANI, NICOLONICOLOPARMIGGIANI0000-0002-4535-5329PIANO, GiovanniGiovanniPIANO0000-0002-9332-5319PILIA, MauraMauraPILIA0000-0001-7397-8091PITTORI, CarlottaCarlottaPITTORI0000-0001-6661-9779Svinkin, D. S.D. S.SvinkinTROIS, ALESSIOALESSIOTROIS0000-0002-3180-6002Tsvetkova, A. E.A. E.TsvetkovaVERCELLONE, STEFANOSTEFANOVERCELLONE0000-0003-1163-1396VITTORINI, VALERIOVALERIOVITTORINI0000-0002-1208-88182022-03-282022-03-2820200004-637Xhttp://hdl.handle.net/20.500.12386/31936GRB 190114C represents a breakthrough for the physics of gamma-ray bursts (GRBs), being the first GRB with delayed emission above 300 GeV, as reported by MAGIC. We present in this paper the sub-MeV/MeV data of the prompt and early afterglow emissions of GRB 190114C, as detected by AGILE and Konus-Wind, in the 20 keV-100 MeV energy range. The first stages of the burst exhibit multiple emission components, associated with an interesting spectral evolution. The first 2 s of the prompt emission can be described by a single "Band-like" spectral component. The successive 4 s show the presence of an additional high-energy spectral component, which quickly evolves into a "hard-flat" component of the νFν spectrum, extending up to 10-100 MeV and likely produced by inverse Compton radiation, whose onset and evolution are clearly shown in our data. After this phase, the νFν spectrum evolves into a "V shape," showing the persistence and spectral hardening of the additional high-energy component in substantial agreement with Fermi and Swift results. We also analyze the first ∼200 s of the early afterglow that show a reflaring episode near T0 + 15 s. We identify a new, so-far-unnoticed flux temporal break near T0 + 100 s, which is detected in hard X-rays by both Konus-Wind and INTEGRAL/SPI-ACS. We find this break incompatible with the commonly assumed adiabatic evolution of a fireball in a constant-density medium. We interpret this break as a consequence of radiative evolution of the early afterglow from a fireball expanding in a wind-like circumburst medium.STAMPAenAGILE and Konus-Wind Observations of GRB 190114C: The Remarkable Prompt and Early Afterglow PhasesArticle10.3847/1538-4357/abc2d42-s2.0-85097490858https://doi.org/10.3847/1538-4357/abc2d4https://iopscience.iop.org/article/10.3847/1538-4357/abc2d42020ApJ...904..133UFIS/05 - ASTRONOMIA E ASTROFISICA