The inner engine of GeV-radiation-emitting gamma-ray bursts

TL;DR

This paper explains how the rotational energy of Kerr black holes in gamma-ray bursts can be extracted using a classical solution, accounting for GeV radiation and ultra-high-energy cosmic rays.

Contribution

It introduces a novel application of Wald's classical solution to extract energy from black holes in gamma-ray bursts, solving a long-standing problem in relativistic astrophysics.

Findings

Energy extraction accelerates protons to 10^{21} eV within microseconds.

The process explains the observed GeV radiation in gamma-ray bursts.

The energy extraction can persist for thousands of years.

Abstract

We motivate how the most recent progress in the understanding the nature of the GeV radiation in most energetic gamma-ray bursts (GRBs), the binary-driven hypernovae (BdHNe), has led to the solution of a forty years unsolved problem in relativistic astrophysics: how to extract the rotational energy from a Kerr black hole for powering synchrotron emission and ultra high-energy cosmic rays. The "inner engine" is identified in the proper use of a classical solution introduced by Wald in 1974 duly extended to the most extreme conditions found around the newborn black hole in a BdHN. The energy extraction process occurs in a sequence impulsive processes each accelerating protons to $10^{21}$ eV in a timescale of $10^{-6}$ s and in presence of an external magnetic field of $10^{14}$ G. Specific example is given for a black hole of initial angular momentum $J=0.3\,M^2$ and mass $M\approx 3\,M_\odot$ leading to the GeV radiation of $10^{49}$ erg$\cdot$s$^{-1}$. The process can energetically continue for thousands of years.