%0 Journal Article
%T Vlasov versus N-body: the Hénon sphere
%+ Institut d'Astrophysique de Paris (IAP)
%A Colombi, S.
%A Sousbie, T.
%A Peirani, S.
%A Plum, G.
%A Suto, Y.
%< avec comité de lecture
%@ 0035-8711
%J Monthly Notices of the Royal Astronomical Society
%I Oxford University Press (OUP): Policy P - Oxford Open Option A
%V 450
%P 3724-3741
%8 2015
%D 2015
%Z 1504.07337
%Z 2015MNRAS.450.3724C
%R 10.1093/mnras/stv819
%K gravitation
%K methods: numerical
%K galaxies: kinematics and dynamics
%K dark matter
%K Astrophysics - Cosmology and Nongalactic Astrophysics
%K Astrophysics - Astrophysics of Galaxies
%Z Sciences of the Universe [physics]
%Z Sciences of the Universe [physics]/Astrophysics [astro-ph]Journal articles
%X 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^{8} particles.
%G English
%2 https://insu.hal.science/insu-03644901/document
%2 https://insu.hal.science/insu-03644901/file/stv819.pdf
%L insu-03644901
%U https://insu.hal.science/insu-03644901
%~ INSU
%~ CNRS
%~ IAP
%~ SORBONNE-UNIVERSITE
%~ SU-INF-2018
%~ SU-SCIENCES
%~ SU-TI
%~ ALLIANCE-SU