Issue |
A&A
Volume 617, September 2018
|
|
---|---|---|
Article Number | A112 | |
Number of page(s) | 8 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361/201832775 | |
Published online | 27 September 2018 |
Coexistence of magneto-rotational and Jeans instabilities in an axisymmetric nebula
1
ENEA, Fusion and Nuclear Safety Department, C.R. Frascati, Via E. Fermi 45, 00044 Frascati (RM), Italy
e-mail: giovanni.montani@enea.it
2
Department of Physics, “Sapienza” University of Rome, P.le Aldo Moro, 5, 00185 Roma, Italy
3
L.T. Calcoli, Via Bergamo, 60, 23807 Merate (LC), Italy
Received:
5
February
2018
Accepted:
18
June
2018
Aims. We analyze the magneto-rotational instability (MRI) effects on gravitational collapse and its influence on the instability critical scale.
Methods. In particular, we study an axisymmetric nonstratified differentially rotating cloud, embedded in a small magnetic field, and we perform a local linear stability analysis, including the self gravity of the system.
Results. We demonstrate that the linear evolution of the perturbations is characterized by the emergence of an anisotropy degree of the perturbed mass densities. Starting with spherical growing overdensities, we see that they naturally acquire an anisotropy of order unity in their shape. Despite the linear character of our analysis, we infer that such a seed of anisotropy can rapidly grow in a nonlinear regime, leading to the formation of filament-like structures. However, we show how such an anisotropy is essentially an intrinsic feature of the Jean instability, and how MRI only plays a significant role in fixing the critical scale of the mode spectrum. We then provide a characterization of the present analysis in terms of the cosmological setting, in order to provide an outlook of how the present results could concern the formation of large-scale structures across the Universe.
Key words: cosmology: theory / large-scale structure of Universe / hydrodynamics
© ESO 2018
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.