Issue |
A&A
Volume 652, August 2021
|
|
---|---|---|
Article Number | A8 | |
Number of page(s) | 7 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/202141040 | |
Published online | 30 July 2021 |
Gravitational collapse from cold uniform asymmetric initial conditions
1
Centro Ricerche Enrico Fermi, Via Panisperna 89 A, 00184 Rome, Italy
e-mail: sylos@cref.it
2
Istituto Nazionale Fisica Nucleare, Unità Roma 1, Dipartimento di Fisica, Università di Roma “Sapienza”, Piazzale Aldo Moro 2, 00185 Roma, Italy
3
Laboratoire de Physique Nucléaire et de Hautes Énergies, UPMC IN2P3 CNRS UMR 7585, Sorbonne Université, 4 place Jussieu, 75252 Paris Cedex 05, France
Received:
9
April
2021
Accepted:
25
May
2021
Using controlled numerical N-body experiments, we show how, in the collapse dynamics of an initially cold and uniform distribution of particles with a generic asymmetric shape, finite N fluctuations and perturbations induced by the anisotropic gravitational field compete to determine the physical properties of the asymptotic quasi-stationary state. When finite N fluctuations dominate the dynamics, the particle energy distribution changes greatly and the final density profile decays outside its core as r−4 with an N-dependent amplitude. On the other hand, in the limit where the anisotropic perturbations dominate, the collapse is softer and the density profile shows a decay as r−3, as is typical of halos in cosmological simulations. However, even in this limit, convergence with N of the macroscopic properties of the virialized system, such as the particle energy distributions, the bound mass, and the density profile, is very slow and not clearly established, including for our largest simulations (with N ∼ 106). Our results illustrate the challenges of accurately simulating the first collapsing structures in standard-type cosmological models.
Key words: methods: numerical / galaxies: formation / galaxies: elliptical and lenticular, cD
© ESO 2021
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