Large-scale magnetic field generation via the kinetic Kelvin-Helmholtz instability in unmagnetized scenarios

Detalhes bibliográficos
Autor(a) principal: Alves, E.P.
Data de Publicação: 2012
Outros Autores: Grismayer, T., Martins, S. F., Fiuza, F., Fonseca, R. A., Silva, L. O.
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: https://ciencia.iscte-iul.pt/public/pub/id/11208
http://hdl.handle.net/10071/7100
Resumo: Collisionless plasma instabilities are fundamental in magnetic field generation in astrophysical scenarios, but their role has been addressed in scenarios where velocity shear is absent. In this work we show that velocity shears must be considered when studying realistic astrophysical scenarios, since these trigger the collisionless Kelvin-Helmholtz instability (KHI). We present the first self-consistent three-dimensional particle-in-cell simulations of the KHI in conditions relevant for unmagnetized relativistic outflows with velocity shear, such as active galactic nuclei and gamma-ray bursts. We show the generation of a strong large-scale DC magnetic field, which extends over the entire shear-surface, reaching thicknesses of a few tens of electron skin depths, and persisting on timescales much longer than the electron timescale. This DC magnetic field is not captured by magnetohydrodynamic models since it arises from intrinsically kinetic effects. Our results indicate that the KHI can generate intense magnetic fields yielding equipartition values up to epsilon(B)/epsilon(p) similar or equal to 10(-3)-10(-2) in the electron timescale. The KHI-induced magnetic fields have a characteristic structure that will lead to a distinct radiation signature and can seed the turbulent dynamo amplification process. The dynamics of the KHI are relevant for non-thermal radiation modeling and can also have a strong impact on the formation of relativistic shocks in presence of velocity shears.
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spelling Large-scale magnetic field generation via the kinetic Kelvin-Helmholtz instability in unmagnetized scenariosInstabilitiesMagnetic fieldsPlasmasCollisionless plasma instabilities are fundamental in magnetic field generation in astrophysical scenarios, but their role has been addressed in scenarios where velocity shear is absent. In this work we show that velocity shears must be considered when studying realistic astrophysical scenarios, since these trigger the collisionless Kelvin-Helmholtz instability (KHI). We present the first self-consistent three-dimensional particle-in-cell simulations of the KHI in conditions relevant for unmagnetized relativistic outflows with velocity shear, such as active galactic nuclei and gamma-ray bursts. We show the generation of a strong large-scale DC magnetic field, which extends over the entire shear-surface, reaching thicknesses of a few tens of electron skin depths, and persisting on timescales much longer than the electron timescale. This DC magnetic field is not captured by magnetohydrodynamic models since it arises from intrinsically kinetic effects. Our results indicate that the KHI can generate intense magnetic fields yielding equipartition values up to epsilon(B)/epsilon(p) similar or equal to 10(-3)-10(-2) in the electron timescale. The KHI-induced magnetic fields have a characteristic structure that will lead to a distinct radiation signature and can seed the turbulent dynamo amplification process. The dynamics of the KHI are relevant for non-thermal radiation modeling and can also have a strong impact on the formation of relativistic shocks in presence of velocity shears.IOP Publishing Ltd2014-05-06T16:26:50Z2012-01-01T00:00:00Z20122014-05-06T16:23:34Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttps://ciencia.iscte-iul.pt/public/pub/id/11208http://hdl.handle.net/10071/7100eng2041-820510.1088/2041-8205/746/2/L14Alves, E.P.Grismayer, T.Martins, S. F.Fiuza, F.Fonseca, R. A.Silva, L. O.info:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2023-11-09T17:55:37Zoai:repositorio.iscte-iul.pt:10071/7100Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T22:28:22.935639Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Large-scale magnetic field generation via the kinetic Kelvin-Helmholtz instability in unmagnetized scenarios
title Large-scale magnetic field generation via the kinetic Kelvin-Helmholtz instability in unmagnetized scenarios
spellingShingle Large-scale magnetic field generation via the kinetic Kelvin-Helmholtz instability in unmagnetized scenarios
Alves, E.P.
Instabilities
Magnetic fields
Plasmas
title_short Large-scale magnetic field generation via the kinetic Kelvin-Helmholtz instability in unmagnetized scenarios
title_full Large-scale magnetic field generation via the kinetic Kelvin-Helmholtz instability in unmagnetized scenarios
title_fullStr Large-scale magnetic field generation via the kinetic Kelvin-Helmholtz instability in unmagnetized scenarios
title_full_unstemmed Large-scale magnetic field generation via the kinetic Kelvin-Helmholtz instability in unmagnetized scenarios
title_sort Large-scale magnetic field generation via the kinetic Kelvin-Helmholtz instability in unmagnetized scenarios
author Alves, E.P.
author_facet Alves, E.P.
Grismayer, T.
Martins, S. F.
Fiuza, F.
Fonseca, R. A.
Silva, L. O.
author_role author
author2 Grismayer, T.
Martins, S. F.
Fiuza, F.
Fonseca, R. A.
Silva, L. O.
author2_role author
author
author
author
author
dc.contributor.author.fl_str_mv Alves, E.P.
Grismayer, T.
Martins, S. F.
Fiuza, F.
Fonseca, R. A.
Silva, L. O.
dc.subject.por.fl_str_mv Instabilities
Magnetic fields
Plasmas
topic Instabilities
Magnetic fields
Plasmas
description Collisionless plasma instabilities are fundamental in magnetic field generation in astrophysical scenarios, but their role has been addressed in scenarios where velocity shear is absent. In this work we show that velocity shears must be considered when studying realistic astrophysical scenarios, since these trigger the collisionless Kelvin-Helmholtz instability (KHI). We present the first self-consistent three-dimensional particle-in-cell simulations of the KHI in conditions relevant for unmagnetized relativistic outflows with velocity shear, such as active galactic nuclei and gamma-ray bursts. We show the generation of a strong large-scale DC magnetic field, which extends over the entire shear-surface, reaching thicknesses of a few tens of electron skin depths, and persisting on timescales much longer than the electron timescale. This DC magnetic field is not captured by magnetohydrodynamic models since it arises from intrinsically kinetic effects. Our results indicate that the KHI can generate intense magnetic fields yielding equipartition values up to epsilon(B)/epsilon(p) similar or equal to 10(-3)-10(-2) in the electron timescale. The KHI-induced magnetic fields have a characteristic structure that will lead to a distinct radiation signature and can seed the turbulent dynamo amplification process. The dynamics of the KHI are relevant for non-thermal radiation modeling and can also have a strong impact on the formation of relativistic shocks in presence of velocity shears.
publishDate 2012
dc.date.none.fl_str_mv 2012-01-01T00:00:00Z
2012
2014-05-06T16:26:50Z
2014-05-06T16:23:34Z
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
format article
status_str publishedVersion
dc.identifier.uri.fl_str_mv https://ciencia.iscte-iul.pt/public/pub/id/11208
http://hdl.handle.net/10071/7100
url https://ciencia.iscte-iul.pt/public/pub/id/11208
http://hdl.handle.net/10071/7100
dc.language.iso.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv 2041-8205
10.1088/2041-8205/746/2/L14
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv IOP Publishing Ltd
publisher.none.fl_str_mv IOP Publishing Ltd
dc.source.none.fl_str_mv reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
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