Magnetars and Gamma Ray Bursts

TL;DR

This paper reviews the millisecond magnetar model as an alternative engine for Long Duration Gamma Ray Bursts, discussing observational constraints, numerical results, and potential explanations for various GRB phenomena.

Contribution

It provides a comprehensive review of the magnetar model's ability to explain GRB features, including constraints, numerical simulations, and potential links to short GRB extended emission.

Findings

Magnetar model can satisfy energetic and outflow constraints.

Numerical simulations highlight the role of progenitor star confinement.

Magnetars may explain extended emission in short GRBs.

Abstract

In the last few years, evidences for a long-lived and sustained engine in Gamma Ray Bursts (GRBs) have increased the attention to the so called millisecond-magnetar model, as a competitive alternative to the standard collapsar scenario. I will review here the key aspects of the {\it millisecond magnetar} model for Long Duration Gamma Ray Bursts (LGRBs). I will briefly describe what constraints, present observations put on any engine model, both in term of energetic, outflow properties, and the relation with the associated Supernova (SN). For each of these I will show how the millisecond magnetar model satisfies the requirements, what are the limits of the model, how can it be further tested, and what observations might be used to discriminate against it. I will also discuss numerical results that show the importance of the confinement by the progenitor star in explaining the formation of a collimated outflow, how a detailed model for the evolution of the central engine can be built, and show that a wide variety of explosive events can be explained by different magnetar parameters. I will conclude with a suggestion that magnetars might be at the origin of the Extended Emission (EE) observed in a significant fraction of Short GRBs.