The time evolution of GRB spectra by a precessing lighthouse gamma jet

Abstract

Inverse Compton Scattering (ICS) by a relativistic electron beam jet at GeV energies (emitted by a compact object as a NS, BH,…), a NSJ, onto thermal BBR photons (from a nearby stellar companion) may originate a collinear gamma jet (GJ). Due to the binary system interaction the GJ precession would blaze suddenly toward the observer leading to a GRB event. The internal GJ cone structure is ruled by relativistic kinematics into a concentric onion-like sequence of photon rings, the softer in the external boundaries, the harder in the inner cone. The pointing and the crossing of such different GJ photon rings to the detector lead to GRB hardness spectral evolution nearly corresponding to that typically observed. Moreover, the expected time integral spectra are also comparable with observed GRB spectra. The total energy input of tens of thousands of such NSJ in an extended galactic halo, mainly cosmic rays electrons, should be reflected into the recent observational evidence (COMPTEL) of a diffuse relic extended halo. Evidences of such precessing jets are offered by the discovery of galactic superluminal sources, HH jets, the outer rings of SN1987A, the Hourglass Nebula, the planetary Egg Nebula, and the binary X-ray pulsar GROJ1744-28.