On the universal GeV emission in binary-driven hypernovae and their inferred morphological structure

We address the significance of the observed GeV emission from \textit{Fermi}-LAT on the understanding of the structure of long GRBs. We examine 82 X-ray Flashs (XRFs), in none of them GeV radiation is observed, adding evidence to the absence of a black hole (BH) formation in their merging process. By examining $329$ Binary-driven Hypernovae (BdHNe) we find that out of $48$ BdHNe observable by \textit{Fermi}-LAT in \textit{only} $21$ of them the GeV emission is observed. The Gev emission in BdHNE follows a universal power-law relation between the luminosity and time, when measured in the rest frame of the source. The power-law index in BdHNe is of $-1.20 \pm 0.04$, very similar to the one discovered in S-GRBs, $-1.29 \pm 0.06$. The GeV emission originates from the newly-born BH and allows to determine its mass and spin. We further give the first evidence for observing a new GRB subclass originating from the merging of a hypernova (HN) and an already formed BH binary companion. We conclude that the GeV emission is a necessary and sufficient condition to confirm the presence of a BH in the hypercritical accretion process occurring in a HN. The remaining $27$ BdHNe, recently identified as sources of flaring in X-rays and soft gamma-rays, have no GeV emission. From this and previous works, we infer that the observability of the GeV emission in some BdHNe is hampered by the presence of the HN ejecta. We conclude that the GeV emission can only be detected when emitted within a half-opening angle $\approx$60$^{\circ}$ normal to the orbital plane of the BdHN.