Implication from GRB 221009A: Can TeV emission come from the GRB prompt phase?

Recently, the B.O.A.T. (“brightest of all time”) gamma-ray burst, dubbed GRB 221009A, was detected by various instruments. Unprecedentedly, the GRB presented very-high-energy (VHE, energy above 0.1 TeV) gamma-ray emission with energy extending above 10 TeV, as reported by the Large High Altitude Air Shower Observatory (LHAASO). We here demonstrate that the VHE and especially >10TeV emission may originate from the internal hadronic dissipation of the GRB, without the need of invoking any exotic processes as suggested by some previous studies. The possible prompt origin of LHAASO photons may imply the first detection of the GRB prompt phase in the VHE regime. We also discuss the constraints on the properties of the GRB ejecta from multiwavelength and multi-messenger observations, which favors a magnetically dominated GRB ejecta. The suggested Poynting-flux-dominated GRB ejecta in this work supports the Blandford & Znajek (BZ) mechanism as the possible central engine model of GRB, as well as the possible strong magnetic dissipation and acceleration.