Turbulence-induced magnetic fields in shock precursors
Abstract
Galactic cosmic rays are believed to be mostly accelerated at supernova shocks. However, the interstellar magnetic field is too weak to efficiently accelerate galactic cosmic rays up to the highest energies, i.e. eV. A stronger magnetic field in the pre-shock region could provide the efficiency required. Bell's cosmic-ray nonresonant streaming instability has been claimed to be responsible for the amplification of precursor magnetic fields. However, an alternative mechanism has been proposed in which the cosmic-ray pressure gradient forms the shock precursor and drives turbulence, amplifying the magnetic field via the small-scale dynamo. A key ingredient for the mechanism to operate are the inhomogeneities present in the interstellar medium (ISM). These inhomogeneities are the consequence of turbulence. In this work we explore the magnetic field amplification in different ISM conditions through 3D MHD numerical simulations.
Keywords
Cite
@article{arxiv.1602.03135,
title = {Turbulence-induced magnetic fields in shock precursors},
author = {Maria Victoria del Valle and Alexandre Lazarian and Reinaldo Santos-Lima},
journal= {arXiv preprint arXiv:1602.03135},
year = {2016}
}
Comments
17 pages, 19 figures; accepted for publication in MNRAS