Electron-scale shear instabilities: magnetic field generation and particle acceleration in astrophysical jets
Autor(a) principal: | |
---|---|
Data de Publicação: | 2014 |
Outros Autores: | , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Texto Completo: | http://hdl.handle.net/10071/6946 |
Resumo: | Strong shear flow regions found in astrophysical jets are shown to be important dissipation regions, where the shear flow kinetic energy flow is converted into electric and magnetic field energy via shear instabilities. The emergence of these self-consistent fields makes shear flows significant sites for radiation emission and particle acceleration. We focus on electron-scale instabilities, namely the collisionless, unmagnetized electron-scale Kelvin–Helmholtz instability (ESKHI) and a large-scale DC magnetic field generation mechanism on the electron scales. We show that these processes are important candidates to generate magnetic fields in the presence of strong velocity shears, which may naturally originate in energetic matter outbursts of active galactic nuclei and gamma-ray bursters. We show that the ESKHI is robust to density jumps between shearing flows, thus operating in various scenarios with different density contrasts. Multidimensional particle-in-cell (PIC) simulations of the ESKHI, performed with OSIRIS, reveal the emergence of a strong and large-scale DC magnetic field component, which is not captured by the standard linear fluid theory. This DC component arises from kinetic effects associated with the thermal expansion of electrons of one flow into the other across the shear layer, whilst ions remain unperturbed due to their inertia. The electron expansion forms DC current sheets, which induce a DC magnetic field. Our results indicate that most of the electromagnetic energy developed in the ESKHI is stored in the DC component, reaching values of equipartition on the order of 10?3 in the electron time-scale, and persists longer than the proton time-scale. Particle scattering/acceleration in the self-generated fields of these shear flow instabilities is also analyzed. |
id |
RCAP_74f1491c13e14b7c14ae5a48cfd6172c |
---|---|
oai_identifier_str |
oai:repositorio.iscte-iul.pt:10071/6946 |
network_acronym_str |
RCAP |
network_name_str |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
repository_id_str |
7160 |
spelling |
Electron-scale shear instabilities: magnetic field generation and particle acceleration in astrophysical jetsPlasma instabilitiesKelvin-HelmholtzVelocity shearJetsStrong shear flow regions found in astrophysical jets are shown to be important dissipation regions, where the shear flow kinetic energy flow is converted into electric and magnetic field energy via shear instabilities. The emergence of these self-consistent fields makes shear flows significant sites for radiation emission and particle acceleration. We focus on electron-scale instabilities, namely the collisionless, unmagnetized electron-scale Kelvin–Helmholtz instability (ESKHI) and a large-scale DC magnetic field generation mechanism on the electron scales. We show that these processes are important candidates to generate magnetic fields in the presence of strong velocity shears, which may naturally originate in energetic matter outbursts of active galactic nuclei and gamma-ray bursters. We show that the ESKHI is robust to density jumps between shearing flows, thus operating in various scenarios with different density contrasts. Multidimensional particle-in-cell (PIC) simulations of the ESKHI, performed with OSIRIS, reveal the emergence of a strong and large-scale DC magnetic field component, which is not captured by the standard linear fluid theory. This DC component arises from kinetic effects associated with the thermal expansion of electrons of one flow into the other across the shear layer, whilst ions remain unperturbed due to their inertia. The electron expansion forms DC current sheets, which induce a DC magnetic field. Our results indicate that most of the electromagnetic energy developed in the ESKHI is stored in the DC component, reaching values of equipartition on the order of 10?3 in the electron time-scale, and persists longer than the proton time-scale. Particle scattering/acceleration in the self-generated fields of these shear flow instabilities is also analyzed.IOP Publishing2014-04-15T13:08:13Z2014-01-01T00:00:00Z20142019-05-20T16:02:17Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttp://hdl.handle.net/10071/6946eng1367-263010.1088/1367-2630/16/3/035007Alves, E. P.Grismayer, T.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:RCAAP2023-11-09T17:44:27Zoai:repositorio.iscte-iul.pt:10071/6946Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T22:21:06.561231Repositório 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 |
Electron-scale shear instabilities: magnetic field generation and particle acceleration in astrophysical jets |
title |
Electron-scale shear instabilities: magnetic field generation and particle acceleration in astrophysical jets |
spellingShingle |
Electron-scale shear instabilities: magnetic field generation and particle acceleration in astrophysical jets Alves, E. P. Plasma instabilities Kelvin-Helmholtz Velocity shear Jets |
title_short |
Electron-scale shear instabilities: magnetic field generation and particle acceleration in astrophysical jets |
title_full |
Electron-scale shear instabilities: magnetic field generation and particle acceleration in astrophysical jets |
title_fullStr |
Electron-scale shear instabilities: magnetic field generation and particle acceleration in astrophysical jets |
title_full_unstemmed |
Electron-scale shear instabilities: magnetic field generation and particle acceleration in astrophysical jets |
title_sort |
Electron-scale shear instabilities: magnetic field generation and particle acceleration in astrophysical jets |
author |
Alves, E. P. |
author_facet |
Alves, E. P. Grismayer, T. Fonseca, R. A. Silva, L. O. |
author_role |
author |
author2 |
Grismayer, T. Fonseca, R. A. Silva, L. O. |
author2_role |
author author author |
dc.contributor.author.fl_str_mv |
Alves, E. P. Grismayer, T. Fonseca, R. A. Silva, L. O. |
dc.subject.por.fl_str_mv |
Plasma instabilities Kelvin-Helmholtz Velocity shear Jets |
topic |
Plasma instabilities Kelvin-Helmholtz Velocity shear Jets |
description |
Strong shear flow regions found in astrophysical jets are shown to be important dissipation regions, where the shear flow kinetic energy flow is converted into electric and magnetic field energy via shear instabilities. The emergence of these self-consistent fields makes shear flows significant sites for radiation emission and particle acceleration. We focus on electron-scale instabilities, namely the collisionless, unmagnetized electron-scale Kelvin–Helmholtz instability (ESKHI) and a large-scale DC magnetic field generation mechanism on the electron scales. We show that these processes are important candidates to generate magnetic fields in the presence of strong velocity shears, which may naturally originate in energetic matter outbursts of active galactic nuclei and gamma-ray bursters. We show that the ESKHI is robust to density jumps between shearing flows, thus operating in various scenarios with different density contrasts. Multidimensional particle-in-cell (PIC) simulations of the ESKHI, performed with OSIRIS, reveal the emergence of a strong and large-scale DC magnetic field component, which is not captured by the standard linear fluid theory. This DC component arises from kinetic effects associated with the thermal expansion of electrons of one flow into the other across the shear layer, whilst ions remain unperturbed due to their inertia. The electron expansion forms DC current sheets, which induce a DC magnetic field. Our results indicate that most of the electromagnetic energy developed in the ESKHI is stored in the DC component, reaching values of equipartition on the order of 10?3 in the electron time-scale, and persists longer than the proton time-scale. Particle scattering/acceleration in the self-generated fields of these shear flow instabilities is also analyzed. |
publishDate |
2014 |
dc.date.none.fl_str_mv |
2014-04-15T13:08:13Z 2014-01-01T00:00:00Z 2014 2019-05-20T16:02:17Z |
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 |
http://hdl.handle.net/10071/6946 |
url |
http://hdl.handle.net/10071/6946 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
1367-2630 10.1088/1367-2630/16/3/035007 |
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 |
publisher.none.fl_str_mv |
IOP Publishing |
dc.source.none.fl_str_mv |
reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação instacron:RCAAP |
instname_str |
Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
instacron_str |
RCAAP |
institution |
RCAAP |
reponame_str |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
collection |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
repository.name.fl_str_mv |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
repository.mail.fl_str_mv |
|
_version_ |
1799134771833470976 |