Radial instability of trapping polytropic spheres

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F47813059%3A19630%2F20%3AA0000041" target="_blank" >RIV/47813059:19630/20:A0000041 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.worldscientific.com/doi/abs/10.1142/S0218271820500303" target="_blank" >https://www.worldscientific.com/doi/abs/10.1142/S0218271820500303</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1142/S0218271820500303" target="_blank" >10.1142/S0218271820500303</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Radial instability of trapping polytropic spheres

Popis výsledku v původním jazyce

We complete the stability study of general-relativistic spherically symmetric polytropic perfect fluid spheres, concentrating our attention on the newly discovered polytropes containing region of trapped null geodesics. We compare the methods of treating the dynamical stability based on the equation governing infinitesimal radial pulsations of the polytropes and the related Sturm-Liouville eigenvalue equation for the eigenmodes governing the pulsations, to the methods of stability analysis based on the energetic considerations. Both methods are applied to determine the stability of the polytropes governed by the polytropic index n in the whole range 0 &lt; n &lt; 5, and the relativistic parameter sigma given by the ratio of the central pressure and energy density, restricted by the causality limit. The critical values of the adiabatic index for stability are determined, together with the critical values of the relativistic parameter sigma. For the dynamical approach, we implemented a numerical method which is independent on the choice of the trial function, and compare its results with the standard trial function approach. We found that the energetic and dynamic method give nearly the same critical values of sigma. We found that all the configurations having trapped null geodesics are unstable according to both methods.

Název v anglickém jazyce

Radial instability of trapping polytropic spheres

Popis výsledku anglicky

We complete the stability study of general-relativistic spherically symmetric polytropic perfect fluid spheres, concentrating our attention on the newly discovered polytropes containing region of trapped null geodesics. We compare the methods of treating the dynamical stability based on the equation governing infinitesimal radial pulsations of the polytropes and the related Sturm-Liouville eigenvalue equation for the eigenmodes governing the pulsations, to the methods of stability analysis based on the energetic considerations. Both methods are applied to determine the stability of the polytropes governed by the polytropic index n in the whole range 0 &lt; n &lt; 5, and the relativistic parameter sigma given by the ratio of the central pressure and energy density, restricted by the causality limit. The critical values of the adiabatic index for stability are determined, together with the critical values of the relativistic parameter sigma. For the dynamical approach, we implemented a numerical method which is independent on the choice of the trial function, and compare its results with the standard trial function approach. We found that the energetic and dynamic method give nearly the same critical values of sigma. We found that all the configurations having trapped null geodesics are unstable according to both methods.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2020

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

International Journal of Modern Physics D

ISSN

0218-2718

e-ISSN

1793-6594

Svazek periodika

29

Číslo periodika v rámci svazku

5

Stát vydavatele periodika

SG - Singapurská republika

Počet stran výsledku

20

Strana od-do

„2050030-1“-„2050030-20“

Kód UT WoS článku

000531817300002

EID výsledku v databázi Scopus

2-s2.0-85082184446