Magnetic-field amplification by turbulence in a relativistic shockpropagating through an inhomogeneous medium

We perform two-dimensional relativistic magnetohydrodynamic simulations of a mildly relativistic shock propagating through an inhomogeneous medium. We show that the postshock region becomes turbulent owing to preshock density inhomogeneity, and the magnetic field is strongly amplified due to the stretching and folding of field lines in the turbulent velocity field. The amplified magnetic field evolves into a filamentary structure in two-dimensional simulations. The magnetic energy spectrum is flatter than the Kolmogorov spectrum and indicates that a so-called small-scale dynamo is occurring in the postshock region. We also find that the amount of magnetic-field amplification depends on the direction of the mean preshock magnetic field, and the timescale of magnetic-field growth depends on the shock strength.

Metadaten
Verfasserangaben:	Yosuke Mizuno, Martin Pohl ORCiD GND, Jacek Niemiec, Bing Zhang, Ken-Ichi Nishikawa, Philip E. Hardee
DOI:	https://doi.org/10.1088/0004-637X/726/2/62
ISSN:	0004-637X
Titel des übergeordneten Werks (Englisch):	The astrophysical journal : an international review of spectroscopy and astronomical physics
Verlag:	IOP Publ. Ltd.
Verlagsort:	Bristol
Publikationstyp:	Wissenschaftlicher Artikel
Sprache:	Englisch
Jahr der Erstveröffentlichung:	2011
Erscheinungsjahr:	2011
Datum der Freischaltung:	26.03.2017
Freies Schlagwort / Tag:	gamma-ray burst: general; magnetohydrodynamics (MHD); methods: numerical; relativistic processes; shock waves; turbulence
Band:	726
Ausgabe:	2
Seitenanzahl:	11
Fördernde Institution:	NSF [AST-0506719, AST-0506666, AST-0908010, AST-0908040, AST-0908362]; NASA [NNG05GK73G, NNX07AJ88G, NNX08AG83G, NNX09AT66G, NNX10AD48G]; MNiSW [N N203 393034]; Foundation for Polish Science through the EEA Financial Mechanism; Altix3700 BX2 at YITP in Kyoto University
Organisationseinheiten:	Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie
Peer Review:	Referiert