Journal Article

On the sideways expansion of relativistic non-spherical shocks and gamma-ray burst afterglows

Maxim Lyutikov

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 421, issue 1, pages 522-524
Published in print March 2012 | ISSN: 0035-8711
Published online March 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.20331.x
On the sideways expansion of relativistic non-spherical shocks and gamma-ray burst afterglows

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Expansion of non-spherical relativistic blast waves is considered in the Kompaneets (the thin-shell) approximation. We find that relativistic motion effectively ‘freezes out’ the lateral dynamics of the shock front: only extremely strongly collimated shocks, with opening angles Δθ≤ 1/Γ2, show appreciable modification of profiles due to sideways expansion. For less collimated profiles, the propagation is nearly ballistic; the sideways expansion of relativistic shocks becomes important only when they become mildly relativistic. Even though the post-shock pressure is equilibrated downstream on the sound crossing time-scale, this does not mean that the shape of the shock changes on the post-shock sound crossing time-scale.

Keywords: hydrodynamics; shock waves; gamma-ray burst: general

Journal Article.  1600 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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