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We report on the observations of gamma-ray burst (GRB) 190114C by the FermiGamma-ray Space Telescope and the Neil Gehrels Swift Observatory. Theearly-time observations reveal multiple emission components that evolveindependently, with a delayed power-law component that exhibits significantspectral attenuation above 40 MeV in the first few seconds of the burst. Thispower-law component transitions to a harder spectrum that is consistent withthe afterglow emission observed at later times. This afterglow component isclearly identifiable in the GBM and BAT light curves as a slowly fadingemission component on which the rest of the prompt emission is superimposed. Asa result, we are able to constrain the transition from internal shock toexternal shock dominated emission. We find that the temporal and spectralevolution of the broadband afterglow emission can be well modeled assynchrotron emission from a forward shock propagating into a wind-likecircumstellar environment and find that high-energy photons observed by FermiLAT are in tension with the theoretical maximum energy that can be achievedthrough synchrotron emission from a shock. These violations of the maximumsynchrotron energy are further compounded by the detection of very high energy(VHE) emission above 300 GeV by MAGIC concurrent with our observations. Weconclude that the observations of VHE photons from GRB 190114C necessitateseither an additional emission mechanism at very high energies that is hidden inthe synchrotron component in the LAT energy range, an acceleration mechanismthat imparts energy to the particles at a rate that is faster than the electronsynchrotron energy loss rate, or revisions of the fundamental assumptions usedin estimating the maximum photon energy attainable through the synchrotronprocess.

Fermi and Swift Observations of GRB 190114C: Tracing the Evolution of High-Energy Emission from Prompt to Afterglow