insu-03644901
https://insu.hal.science/insu-03644901
https://insu.hal.science/insu-03644901/document
https://insu.hal.science/insu-03644901/file/stv819.pdf
arxiv:1504.07337
doi:10.1093/mnras/stv819
[INSU] INSU - Institut National des Sciences de l'Univers
[CNRS] CNRS - Centre national de la recherche scientifique
[IAP] Institut d'Astrophysique de Paris
[SORBONNE-UNIVERSITE] Sorbonne Université
[SU-INF-2018] SORBONNE université <2018
[SU-SCIENCES] Faculté des Sciences de Sorbonne Université
[SU-TI] Sorbonne Université - Texte Intégral
[ALLIANCE-SU] Alliance Sorbonne Université
Vlasov versus N-body: the Hénon sphere
Colombi, S.
Sousbie, T.
Peirani, S.
Plum, G.
Suto, Y.
[SDU] Sciences of the Universe [physics]
[SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph]
ART
gravitation
methods: numerical
galaxies: kinematics and dynamics
dark matter
Astrophysics - Cosmology and Nongalactic Astrophysics
Astrophysics - Astrophysics of Galaxies
We perform a detailed comparison of the phase-space density traced by the particle distribution in GADGET simulations to the result obtained with a spherical Vlasov solver using the splitting algorithm. The systems considered are apodized Hénon spheres with two values of the virial ratio, R ≃ 0.1 and 0.5. After checking that spherical symmetry is well preserved by the N-body simulations, visual and quantitative comparisons are performed. In particular, we introduce new statistics, correlators and entropic estimators, based on the likelihood of whether N-body simulations actually trace randomly the Vlasov phase-space density. When taking into account the limits of both the N-body and the Vlasov codes, namely collective effects due to the particle shot noise in the first case and diffusion and possible non-linear instabilities due to finite resolution of the phase-space grid in the second case, we find a spectacular agreement between both methods, even in regions of phase-space where non-trivial physical instabilities develop. However, in the colder case, R = 0.1, it was not possible to prove actual numerical convergence of the N-body results after a number of dynamical times, even with N = 10<SUP>8</SUP> particles.
2015
2022-04-28
en
Monthly Notices of the Royal Astronomical Society
Oxford University Press (OUP): Policy P - Oxford Open Option A