Electrically non-neutral ground states of stars
| Autor: | Hund, Parker, Kiessling, Michael K. -H. |
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| Rok vydání: | 2021 |
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| Zdroj: | Physical Review D, vol. 103, art. 043004 (2021) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevD.103.043004 |
| Popis: | To approximately compute the non-relativistic ground state of an electrically non-neutral star, an exactly solvable model was recently introduced, and partly solved, by Krivoruchenko, Nadyozhin, and Yudin. The model generalizes the well-known Lane--Emden equation of a polytropic gas ball of index $n=1$ to a two-fluid setting. Here its complete solution is presented in terms of simple elementary functions; it is also generalized to a more-than-two-fluid setting where it remains exactly solvable. It is shown that, given the number of nuclei, a maximal negatively and a maximal positively charged solution exists, plus a continuous family of solutions which interpolates between these extremes. Numerical comparisons show that this exactly solvable model captures the qualitative behavior of the more physical model it is supposed to approximate. Furthermore, it correctly answers the question: how non-neutral can the star be? The answer is independent of the speed of light $c$ and the Planck quantum $h$. It supports Penrose's weak cosmic censorship hypothesis, in the sense that the bounds on the excess charge are compatible with the bound on the charge of a Reissner--Weyl--Nordstr\"om black hole. Comment: 26 pages, 15 figures, to appear in Phys. Rev. D. This preprint is a significant expansion (with its own new title) of about 2/3 of the 18 page preprint arXiv:2008.04501v1 that was split into two pieces. The other 1/3 of arXiv:2008.04501v1 was slightly expanded and became arXiv:2008.04501v2 (with the original title) that will appear in Am. J. Phys |
| Databáze: | arXiv |
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