Publication Date:
2015-05-20
Description:
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.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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