Gamma-ray burst phenomenology, shock dynamo, and the first magnetic fields

Andrei Gruzinov

doi:10.1086/324223

Gamma-ray burst phenomenology, shock dynamo, and the first magnetic fields

Andrei Gruzinov

Research output: Contribution to journal › Article › peer-review

Abstract

A relativistic collisionless shock propagating into an unmagnetized medium leaves behind a strong large-scale magnetic field. This seems to follow from two assumptions: (1) Gamma-ray burst (GRB) afterglows are explained by synchrotron emission of a relativistic shock. (2) The magnetic field cannot exist on microscopic scales only; it would decay by phase-space mixing. Assumption 1 is generally accepted because of an apparent success of the shock synchrotron phenomenological model of GRB afterglows. Assumption 2 is confirmed in this work by a low-dimensional numerical simulation. One may hypothesize that relativistic shock velocities are not essential for the magnetic field generation and that all collisionless shocks propagating into an unmagnetized medium generate strong large-scale magnetic fields. If this hypothesis is true, the first cosmical magnetic fields could have been generated in shocks of the first virialized objects.

Original language	English (US)
Pages (from-to)	L15-L18
Journal	Astrophysical Journal
Volume	563
Issue number	1 PART 2
DOIs	https://doi.org/10.1086/324223
State	Published - Dec 10 2001

Keywords

Magnetic fields
Shock waves

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1086/324223

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abstract = "A relativistic collisionless shock propagating into an unmagnetized medium leaves behind a strong large-scale magnetic field. This seems to follow from two assumptions: (1) Gamma-ray burst (GRB) afterglows are explained by synchrotron emission of a relativistic shock. (2) The magnetic field cannot exist on microscopic scales only; it would decay by phase-space mixing. Assumption 1 is generally accepted because of an apparent success of the shock synchrotron phenomenological model of GRB afterglows. Assumption 2 is confirmed in this work by a low-dimensional numerical simulation. One may hypothesize that relativistic shock velocities are not essential for the magnetic field generation and that all collisionless shocks propagating into an unmagnetized medium generate strong large-scale magnetic fields. If this hypothesis is true, the first cosmical magnetic fields could have been generated in shocks of the first virialized objects.",

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Gamma-ray burst phenomenology, shock dynamo, and the first magnetic fields

Abstract

Keywords

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