Models of cuspy triaxial stellar systems - I. Stability and chaoticity

Autores
Zorzi, Alejandra Francisca; Muzzio, Juan Carlos
Año de publicación
2012
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
We used the N-body code of Hernquist & Ostriker to build a dozen cuspy (γ ≃ 1) triaxial models of stellar systems through dissipationless collapses of initially spherical distributions of 106 particles. We chose four sets of initial conditions that resulted in models morphologically resembling E2, E3, E4 and E5 galaxies, respectively. Within each set, three different seed numbers were selected for the random number generator used to create the initial conditions, so that the three models of each set are statistically equivalent. We checked the stability of our models using the values of their central densities and of their moments of inertia, which turned out to be very constant indeed. The changes of those values were all less than 3 per cent over one Hubble time and, moreover, we show that the most likely cause of those changes are relaxation effects in the numerical code. We computed the six Lyapunov exponents of nearly 5000 orbits in each model in order to recognize regular, partially and fully chaotic orbits. All the models turned out to be highly chaotic, with less than 25 per cent of their orbits being regular. We conclude that it is quite possible to obtain cuspy triaxial stellar models that contain large fractions of chaotic orbits and are highly stable. The difficulty in building such models with the method of Schwarzschild should be attributed to the method itself and not to physical causes.
Facultad de Ciencias Astronómicas y Geofísicas
Instituto de Astrofísica de La Plata
Materia
Ciencias Astronómicas
Chaos
Galaxies: elliptical and lenticular, cD
Galaxies: kinematics and dynamics
Methods: numerical
Nivel de accesibilidad
acceso abierto
Condiciones de uso
http://creativecommons.org/licenses/by-nc-sa/4.0/
Repositorio
SEDICI (UNLP)
Institución
Universidad Nacional de La Plata
OAI Identificador
oai:sedici.unlp.edu.ar:10915/83972

id SEDICI_3a905580dd9d67463bc6399337b34c59
oai_identifier_str oai:sedici.unlp.edu.ar:10915/83972
network_acronym_str SEDICI
repository_id_str 1329
network_name_str SEDICI (UNLP)
spelling Models of cuspy triaxial stellar systems - I. Stability and chaoticityZorzi, Alejandra FranciscaMuzzio, Juan CarlosCiencias AstronómicasChaosGalaxies: elliptical and lenticular, cDGalaxies: kinematics and dynamicsMethods: numericalWe used the N-body code of Hernquist & Ostriker to build a dozen cuspy (γ ≃ 1) triaxial models of stellar systems through dissipationless collapses of initially spherical distributions of 10<SUP>6</SUP> particles. We chose four sets of initial conditions that resulted in models morphologically resembling E2, E3, E4 and E5 galaxies, respectively. Within each set, three different seed numbers were selected for the random number generator used to create the initial conditions, so that the three models of each set are statistically equivalent. We checked the stability of our models using the values of their central densities and of their moments of inertia, which turned out to be very constant indeed. The changes of those values were all less than 3 per cent over one Hubble time and, moreover, we show that the most likely cause of those changes are relaxation effects in the numerical code. We computed the six Lyapunov exponents of nearly 5000 orbits in each model in order to recognize regular, partially and fully chaotic orbits. All the models turned out to be highly chaotic, with less than 25 per cent of their orbits being regular. We conclude that it is quite possible to obtain cuspy triaxial stellar models that contain large fractions of chaotic orbits and are highly stable. The difficulty in building such models with the method of Schwarzschild should be attributed to the method itself and not to physical causes.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plata2012info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionArticulohttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdf1955-1963http://sedici.unlp.edu.ar/handle/10915/83972enginfo:eu-repo/semantics/altIdentifier/issn/0035-8711info:eu-repo/semantics/altIdentifier/doi/10.1111/j.1365-2966.2012.21023.xinfo:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by-nc-sa/4.0/Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)reponame:SEDICI (UNLP)instname:Universidad Nacional de La Platainstacron:UNLP2025-09-29T11:16:05Zoai:sedici.unlp.edu.ar:10915/83972Institucionalhttp://sedici.unlp.edu.ar/Universidad públicaNo correspondehttp://sedici.unlp.edu.ar/oai/snrdalira@sedici.unlp.edu.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:13292025-09-29 11:16:05.352SEDICI (UNLP) - Universidad Nacional de La Platafalse
dc.title.none.fl_str_mv Models of cuspy triaxial stellar systems - I. Stability and chaoticity
title Models of cuspy triaxial stellar systems - I. Stability and chaoticity
spellingShingle Models of cuspy triaxial stellar systems - I. Stability and chaoticity
Zorzi, Alejandra Francisca
Ciencias Astronómicas
Chaos
Galaxies: elliptical and lenticular, cD
Galaxies: kinematics and dynamics
Methods: numerical
title_short Models of cuspy triaxial stellar systems - I. Stability and chaoticity
title_full Models of cuspy triaxial stellar systems - I. Stability and chaoticity
title_fullStr Models of cuspy triaxial stellar systems - I. Stability and chaoticity
title_full_unstemmed Models of cuspy triaxial stellar systems - I. Stability and chaoticity
title_sort Models of cuspy triaxial stellar systems - I. Stability and chaoticity
dc.creator.none.fl_str_mv Zorzi, Alejandra Francisca
Muzzio, Juan Carlos
author Zorzi, Alejandra Francisca
author_facet Zorzi, Alejandra Francisca
Muzzio, Juan Carlos
author_role author
author2 Muzzio, Juan Carlos
author2_role author
dc.subject.none.fl_str_mv Ciencias Astronómicas
Chaos
Galaxies: elliptical and lenticular, cD
Galaxies: kinematics and dynamics
Methods: numerical
topic Ciencias Astronómicas
Chaos
Galaxies: elliptical and lenticular, cD
Galaxies: kinematics and dynamics
Methods: numerical
dc.description.none.fl_txt_mv We used the N-body code of Hernquist & Ostriker to build a dozen cuspy (γ ≃ 1) triaxial models of stellar systems through dissipationless collapses of initially spherical distributions of 10<SUP>6</SUP> particles. We chose four sets of initial conditions that resulted in models morphologically resembling E2, E3, E4 and E5 galaxies, respectively. Within each set, three different seed numbers were selected for the random number generator used to create the initial conditions, so that the three models of each set are statistically equivalent. We checked the stability of our models using the values of their central densities and of their moments of inertia, which turned out to be very constant indeed. The changes of those values were all less than 3 per cent over one Hubble time and, moreover, we show that the most likely cause of those changes are relaxation effects in the numerical code. We computed the six Lyapunov exponents of nearly 5000 orbits in each model in order to recognize regular, partially and fully chaotic orbits. All the models turned out to be highly chaotic, with less than 25 per cent of their orbits being regular. We conclude that it is quite possible to obtain cuspy triaxial stellar models that contain large fractions of chaotic orbits and are highly stable. The difficulty in building such models with the method of Schwarzschild should be attributed to the method itself and not to physical causes.
Facultad de Ciencias Astronómicas y Geofísicas
Instituto de Astrofísica de La Plata
description We used the N-body code of Hernquist & Ostriker to build a dozen cuspy (γ ≃ 1) triaxial models of stellar systems through dissipationless collapses of initially spherical distributions of 10<SUP>6</SUP> particles. We chose four sets of initial conditions that resulted in models morphologically resembling E2, E3, E4 and E5 galaxies, respectively. Within each set, three different seed numbers were selected for the random number generator used to create the initial conditions, so that the three models of each set are statistically equivalent. We checked the stability of our models using the values of their central densities and of their moments of inertia, which turned out to be very constant indeed. The changes of those values were all less than 3 per cent over one Hubble time and, moreover, we show that the most likely cause of those changes are relaxation effects in the numerical code. We computed the six Lyapunov exponents of nearly 5000 orbits in each model in order to recognize regular, partially and fully chaotic orbits. All the models turned out to be highly chaotic, with less than 25 per cent of their orbits being regular. We conclude that it is quite possible to obtain cuspy triaxial stellar models that contain large fractions of chaotic orbits and are highly stable. The difficulty in building such models with the method of Schwarzschild should be attributed to the method itself and not to physical causes.
publishDate 2012
dc.date.none.fl_str_mv 2012
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
Articulo
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://sedici.unlp.edu.ar/handle/10915/83972
url http://sedici.unlp.edu.ar/handle/10915/83972
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/issn/0035-8711
info:eu-repo/semantics/altIdentifier/doi/10.1111/j.1365-2966.2012.21023.x
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-sa/4.0/
Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
eu_rights_str_mv openAccess
rights_invalid_str_mv http://creativecommons.org/licenses/by-nc-sa/4.0/
Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
dc.format.none.fl_str_mv application/pdf
1955-1963
dc.source.none.fl_str_mv reponame:SEDICI (UNLP)
instname:Universidad Nacional de La Plata
instacron:UNLP
reponame_str SEDICI (UNLP)
collection SEDICI (UNLP)
instname_str Universidad Nacional de La Plata
instacron_str UNLP
institution UNLP
repository.name.fl_str_mv SEDICI (UNLP) - Universidad Nacional de La Plata
repository.mail.fl_str_mv alira@sedici.unlp.edu.ar
_version_ 1844616032805715968
score 13.070432