Relativistic Jets and Long-Duration Gamma-ray Bursts from the Birth of Magnetars

Abstract

We present time-dependent axisymmetric magnetohydrodynamic simulations of the interaction of a relativistic magnetized wind produced by a proto-magnetar with a surrounding stellar envelope, in the first $\sim 10$ seconds after core collapse. We inject a super-magnetosonic wind with $\dot{E}=10^{51}$ ergs s${}^{-1}$ into a cavity created by an outgoing supernova shock. A strong toroidal magnetic field builds up in the bubble of plasma and magnetic field that is at first inertially confined by the progenitor star. This drives a jet out along the polar axis of the star, even though the star and the magnetar wind are each spherically symmetric. The jet has the properties needed to produce a long-duration gamma-ray burst (GRB). At $\sim 5$ s after core bounce, the jet has escaped the host star and the Lorentz factor of the material in the jet at large radii $\sim 10^{11}$ cm is similar to that in the magnetar wind near the source. Most of the spindown power of the central magnetar escapes via the relativistic jet. There are fluctuations in the Lorentz factor and energy flux in the jet on $\sim 0.01-0.1$ second timescale. These may contribute to variability in GRB emission (e.g., via internal shocks).

5 pages, 3 figures, accepted in MNRAS letter, presented at the conference "Astrophysics of Compact Objects", 1-7 July, Huangshan, China

References in corpus (6)

• The Supernova -- Gamma-Ray Burst Connection
• Relativistic MHD Winds from Rotating Neutron Stars
• Magnetar Driven Bubbles and the Origin of Collimated Outflows in Gamma-ray Bursts
• Gamma Ray Bursts as Electromagnetic Outflows
• Magnetar-Driven Magnetic Tower as a Model for Gamma-Ray Bursts and Asymmetric Supernovae
• Electromagnetic Fields in Jets

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• X-ray flares, neutrino cooled disks, and the dynamics of late accretion in GRB engines
• Gamma Ray Burst engine activity within the quark nova scenario: Prompt emission, X-ray Plateau, and sharp drop-off
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