Radiative striped wind model for gamma-ray bursts

TL;DR

This paper revisits the striped wind model for gamma-ray bursts, incorporating radiation effects and analyzing how different assumptions influence the wind's dynamics, photon production, and potential spectral implications.

Contribution

It introduces a detailed treatment of radiation in the striped wind model, exploring two scenarios and their impact on reconnection layer properties and photon production in GRBs.

Findings

Radiation streaming affects reconnection layer properties.

Photon diffusion is limited below a certain radius, influencing photon density.

Enhanced photon production occurs above a critical radius, impacting GRB spectra.

Abstract

In this paper we revisit the striped wind model in which the wind is accelerated by magnetic reconnection. In our treatment, radiation is included as an independent component, and two scenarios are considered. In the first one, radiation cannot stream efficiently through the reconnection layer, while the second scenario assumes that radiation is homogeneous in the striped wind. We show how these two assumptions affect the dynamics. In particular, we find that the asymptotic radial evolution of the Lorentz factor is not strongly modified whether radiation can stream through the reconnection layer or not. On the other hand, we show that the width, density and temperature of the reconnection layer are strongly dependent on these assumptions. We then apply the model to the gamma-ray burst context and find that photons cannot diffuse efficiently through the reconnection layer below radius $r_{\rm D}^{\Delta} \sim 10^{10.5}$ cm, which is about an order of magnitude below the photospheric radius. Above $r_{\rm D}^{\Delta}$, the dynamics asymptotes to the solution of the scenario in which radiation can stream through the reconnection layer. As a result, the density of the current sheet increases sharply, providing efficient photon production by the Bremsstrahlung process which could have profound influence on the emerging spectrum. This effect might provide a solution to the soft photon problem in GRBs.