Could cosmic rays affect instabilities in the Transition layer of nonrealativistic collisionless shocks?
- There is an observational correlation between astrophysical shocks and nonthermal particle distributions extending to high energies. As a first step toward investigating the possible feedback of these particles on the shock at the microscopic level, we perform particle-in-cell (PIC) simulations of a simplified environment consisting of uniform, interpenetrating plasmas, both with and without an additional population of cosmic rays. We vary the relative density of the counterstreaming plasmas, the strength of a homogeneous parallel magnetic field, and the energy density in cosmic rays. We compare the early development of the unstable spectrum for selected configurations without cosmic rays to the growth rates predicted from linear theory, for assurance that the system is well represented by the PIC technique. Within the parameter space explored, we do not detect an unambiguous signature of any cosmic-ray-induced effects on the microscopic instabilities that govern the formation of a shock. We demonstrate that an overly coarseThere is an observational correlation between astrophysical shocks and nonthermal particle distributions extending to high energies. As a first step toward investigating the possible feedback of these particles on the shock at the microscopic level, we perform particle-in-cell (PIC) simulations of a simplified environment consisting of uniform, interpenetrating plasmas, both with and without an additional population of cosmic rays. We vary the relative density of the counterstreaming plasmas, the strength of a homogeneous parallel magnetic field, and the energy density in cosmic rays. We compare the early development of the unstable spectrum for selected configurations without cosmic rays to the growth rates predicted from linear theory, for assurance that the system is well represented by the PIC technique. Within the parameter space explored, we do not detect an unambiguous signature of any cosmic-ray-induced effects on the microscopic instabilities that govern the formation of a shock. We demonstrate that an overly coarse distribution of energetic particles can artificially alter the statistical noise that produces the perturbative seeds of instabilities, and that such effects can be mitigated by increasing the density of computational particles.…
Verfasserangaben: | Thomas Stroman, Martin PohlORCiDGND, Jacek Niemiec, Antoine Bret |
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DOI: | https://doi.org/10.1088/0004-637X/746/1/24 |
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: | 2012 |
Erscheinungsjahr: | 2012 |
Datum der Freischaltung: | 26.03.2017 |
Freies Schlagwort / Tag: | cosmic rays; instabilities; plasmas; shock waves |
Band: | 746 |
Ausgabe: | 1 |
Seitenanzahl: | 10 |
Fördernde Institution: | National Science Foundation [PHY05-51164]; Spanish Ministerio de Educacion y Ciencia [ENE2009-09276]; Consejeria de Educacion y Ciencia de la Junta de Comunidades de Castilla-La Mancha [PEII11-0056-1890]; MNiSW [N N203 393034]; Foundation for Polish Science through the HOMING through EEA Financial Mechanism; Deutsche Forschungsgemeinschaft [PO 1508/1-1] |
Organisationseinheiten: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
Peer Review: | Referiert |