Axisymmetric magnetohydrodynamic simulations of the collapsar model for gamma-ray bursts

Daniel Proga, Andrew I. Macfadyen, Philip J. Armitage, Mitchell C. Begelman

    Research output: Contribution to journalArticle

    Abstract

    We present results from axisymmetric, time-dependent magnetohydrodynamic (MHD) simulations of the collapsar model for gamma-ray bursts. We begin the simulations after the 1.7 M iron core of a 25 M presupernova star has collapsed and study the ensuing accretion of the 7 M helium envelope onto the central black hole formed by the collapsed iron core. We consider a spherically symmetric progenitor model but with spherical symmetry broken by the introduction of a small, latitude-dependent angular momentum and a weak radial magnetic field. Our MHD simulations include a realistic equation of state, neutrino cooling, photodisintegration of helium, and resistive heating. Our main conclusion is that, within the collapsar model, MHD effects alone are able to launch, accelerate, and sustain a strong polar outflow. We also find that the outflow is Poynting flux-dominated and note that this provides favorable initial conditions for the subsequent production of a baryon-poor fireball.

    Original languageEnglish (US)
    JournalAstrophysical Journal
    Volume599
    Issue number1 II
    DOIs
    Publication statusPublished - Dec 10 2003

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    Keywords

    • Accretion, accretion disks
    • Gamma rays: bursts
    • Methods: numerical
    • MHD
    • Stars: winds, outflows

    ASJC Scopus subject areas

    • Space and Planetary Science

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