A three stage model for the inner engine of GRBs: Prompt emission and early afterglow

TL;DR

This paper proposes a three-stage model within the Quark-nova scenario to explain the prompt emission and early afterglow features of long Gamma-Ray Bursts, incorporating accretion processes and jet interactions.

Contribution

It introduces a novel three-stage model explaining GRB prompt emission and early afterglow through quark-star and black-hole evolution within supernovae.

Findings

Model accounts for energies and timescales of GRBs.

Explains early X-ray afterglow features.

Predicts flaring activity from jet interactions.

Abstract

We describe a model within the ``Quark-nova'' scenario to interpret the recent observations of early X-ray afterglows of long Gamma-Ray Bursts (GRB) with the Swift satellite. This is a three-stage model within the context of a core-collapse supernova. STAGE 1 is an accreting (proto-) neutron star leading to a possible delay between the core collapse and the GRB. STAGE 2 is accretion onto a quark-star, launching an ultrarelativistic jet generating the prompt GRB. This jet also creates the afterglow as the jet interacts with the surrounding medium creating an external shock. Slower shells ejected from the quark star (during accretion), can re-energize the external shock leading to a flatter segment in the X-ray afterglow. STAGE 3, which occurs only if the quark-star collapses to form a black-hole, consists of an accreting black-hole. The jet launched in this accretion process interacts with the preceding quark star jet, and could generate the flaring activity frequently seen in early X-ray afterglows. Alternatively, a STAGE 2b can occur in our model if the quark star does not collapse to a black hole. The quark star in this case can then spin down due to magnetic braking, and the spin down energy may lead to flattening in the X-ray afterglow as well. This model seems to account for both the energies and the timescales of GRBs, in addition to the newly discovered early X-ray afterglow features.