Abstract
The binary-driven hypernova (BdHN) model has been introduced in the past years, to explain a subfamily of gamma-ray bursts (GRBs) with energies Eiso ≥ 1052 erg associated with type Ic supernovae. Such BdHNe have as progenitor a tight binary system composed of a carbon-oxigen (CO) core and a neutron star undergoing an induced gravitational collapse to a black hole, triggered by the CO core explosion as a supernova (SN). This collapse produces an optically-thick e+e- plasma, which expands and impacts onto the SN ejecta. This process is here considered as a candidate for the production of X-ray flares, which are frequently observed following the prompt emission of GRBs. In this work we follow the evolution of the e+e- plasma as it interacts with the SN ejecta, by solving the equations of relativistic hydrodynamics numerically. Our results are compatible with the Lorentz factors estimated for the sources that produce the flares, of typically Γ ≲ 4.
Highlights
The binary-driven hypernova (BdHN) model has been introduced in the past years, to explain a subfamily of gamma-ray bursts (GRBs) with energies Eiso ≥ 1052 erg associated with type Ic supernovae
Such binary-driven hypernovae (BdHNe) have as progenitor a tight binary system composed of a carbon-oxigen (CO) core and a neutron star undergoing an induced gravitational collapse to a black hole, triggered by the CO core explosion as a supernova (SN)
This collapse produces an optically-thick e+e− plasma, which expands and impacts onto the SN ejecta. This process is here considered as a candidate for the production of X-ray flares, which are frequently observed following the prompt emission of GRBs
Summary
The induced gravitational collapse (IGC) (see, e.g., [1], [2], [3]) has been proposed in the past years, as a way to explain a sub-class of long gamma-ray bursts (GRBs) called binary-driven hypernovae (BdHNe), characterised by an isotropic energy Eiso ≥ 1052 erg and a rest-frame spectral peak energy between 0.2 and 2 MeV. If the core-collapse of the CO star produces a supernova explosion, the ejected material may trigger an hypercritical accretion process onto the NS, due to a copious neutrino emission and the trapping of photons within the accretion flow This process can cause the NS to collapse as well, forming a black hole (BH). It has been proposed in [4] and, e.g., [5], that such collapse can lead to the formation of an e+e− plasma, that later expands and interacts with the SN ejecta, producing a GRB These differences in the features of the prompt emission and the flares can be explained in terms of the IGC model. In this work we describe numerically the evolution of the plasma along different directions, and study the compatibility of the IGC model with some of the abovementioned observational features
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