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The physical mechanism of gamma-ray bursts (GRBs) remains elusive. One of thedifficulties in nailing down their physical mechanism comes from the fact thatthere has been no clear observational evidence on how far from the centralengine the prompt gamma-rays of GRBs are emitted while the competing physicalmechanisms predict different characteristic distances. Here we present a simplestudy addressing this question by making use of the "high-latitude emission"(HLE). We show that our detailed numerical modeling exhibits a clear signatureof HLE in the decaying phase of "broad pulses" of GRBs. We show that the HLEcan emerge as a prominent spectral break in $F_{\nu}$ spectra and dominate thepeak of $\nu F_{\nu}$ spectra even while the "line-of-sight emission" (LoSE) isstill ongoing, hence providing a new view of HLE emergence. We remark that this"HLE break" could be hidden in some broad pulses, depending on the proximitybetween the peak energies of the LoSE and the HLE. Also, we present threeexamples of Fermi-GBM GRBs with broad pulses that exhibit the HLE signature. Weshow that their gamma-ray emitting region should be located at $\sim 10^{16}$cm from the central engine, which disfavors the photosphere models andsmall-radii internal shock models but favors magnetic dissipation models with alarge emission radius.

Evidence of high latitude emission in the prompt phase of GRBs: How far from the central engine are the GRBs produced?