%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 = 108 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