Nonlinear instability and solitons in a self-gravitating fluid
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| Main Authors: | , , , , |
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| Format: | Preprint |
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2023
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| _version_ | 1866916131739009024 |
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| author | Koutsokostas, G. N. Sypsas, S. Evnin, O. Horikis, T. P. Frantzeskakis, D. J. |
| author_facet | Koutsokostas, G. N. Sypsas, S. Evnin, O. Horikis, T. P. Frantzeskakis, D. J. |
| contents | We study a spherical, self-gravitating fluid model, which finds applications in cosmic structure formation. We argue that since the system features nonlinearity and gravity-induced dispersion, the emergence of solitons becomes possible. We thus employ a multiscale expansion method to study, in the weakly nonlinear regime, the evolution of small-amplitude perturbations around the equilibrium state. This way, we derive a spherical nonlinear Schr{ö}dinger (NLS) equation that governs the envelope of the perturbations. The effective NLS description allows us to predict a "nonlinear instability" (occurring in the nonlinear regime of the system), namely, the modulational instability which, in turn, may give rise to spherical soliton states. The latter feature a very slow (polynomial) curvature-induced decay in time. The soliton profiles may be used to describe the shape of dark matter halos at the rims of the galaxies. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2312_16577 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Nonlinear instability and solitons in a self-gravitating fluid Koutsokostas, G. N. Sypsas, S. Evnin, O. Horikis, T. P. Frantzeskakis, D. J. Pattern Formation and Solitons General Relativity and Quantum Cosmology Mathematical Physics Exactly Solvable and Integrable Systems We study a spherical, self-gravitating fluid model, which finds applications in cosmic structure formation. We argue that since the system features nonlinearity and gravity-induced dispersion, the emergence of solitons becomes possible. We thus employ a multiscale expansion method to study, in the weakly nonlinear regime, the evolution of small-amplitude perturbations around the equilibrium state. This way, we derive a spherical nonlinear Schr{ö}dinger (NLS) equation that governs the envelope of the perturbations. The effective NLS description allows us to predict a "nonlinear instability" (occurring in the nonlinear regime of the system), namely, the modulational instability which, in turn, may give rise to spherical soliton states. The latter feature a very slow (polynomial) curvature-induced decay in time. The soliton profiles may be used to describe the shape of dark matter halos at the rims of the galaxies. |
| title | Nonlinear instability and solitons in a self-gravitating fluid |
| topic | Pattern Formation and Solitons General Relativity and Quantum Cosmology Mathematical Physics Exactly Solvable and Integrable Systems |
| url | https://arxiv.org/abs/2312.16577 |