Gravitational instability of polytropic spheres containing region of trapped null geodesics: a possible explanation of central supermassive black holes in galactic halos

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F47813059%3A19240%2F17%3AA0000015" target="_blank" >RIV/47813059:19240/17:A0000015 - isvavai.cz</a>

Result on the web

<a href="http://iopscience.iop.org/article/10.1088/1475-7516/2017/06/056/meta" target="_blank" >http://iopscience.iop.org/article/10.1088/1475-7516/2017/06/056/meta</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1088/1475-7516/2017/06/056" target="_blank" >10.1088/1475-7516/2017/06/056</a>

Result language

angličtina

Original language name

Gravitational instability of polytropic spheres containing region of trapped null geodesics: a possible explanation of central supermassive black holes in galactic halos

Original language description

We study behaviour of gravitational waves in the recently introduced general relativistic polytropic spheres containing a region of trapped null geodesics extended around radius of the stable null circular geodesic that can exist for the polytropic index N &gt; 2.138 and the relativistic parameter, giving ratio of the central pressure p_c to the central energy density rho_c, higher than sigma = 0.677. In the trapping zones of such polytropes, the effective potential of the axial gravitational wave perturbations resembles those related to the ultracompact uniform density objects, giving thus similar long-lived axial gravitational modes. These long-lived linear perturbations are related to the stable circular null geodesic and due to additional non-linear phenomena could lead to conversion of the trapping zone to a black hole. We give in the eikonal limit examples of the long-lived gravitational modes, their oscillatory frequencies and slow damping rates, for the trapping zones of the polytropes with N is an element of (2.138, 4). However, in the trapping polytropes the long-lived damped modes exist only for very large values of the multipole number l &gt; 50, while for smaller values of l the numerical calculations indicate existence of fast growing unstable axial gravitational modes. We demonstrate that for polytropes with N &gt;= 3.78, the trapping region is by many orders smaller than extension of the polytrope, and the mass contained in the trapping zone is about 10^(-3) of the total mass of the polytrope. Therefore, the gravitational instability of such trapping zones could serve as a model explaining creation of central supermassive black holes in galactic halos or galaxy clusters.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

<a href="/en/project/GB14-37086G" target="_blank" >GB14-37086G: Albert Einstein Center for Gravitation and Astrophysics</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)<br>S - Specificky vyzkum na vysokych skolach<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2017

Confidentiality

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

Name of the periodical

Journal of Cosmology and Astroparticle Physics

ISSN

1475-7516

e-ISSN

—

Volume of the periodical

neuveden

Issue of the periodical within the volume

6

Country of publishing house

GB - UNITED KINGDOM

Number of pages

27

Pages from-to

'056-i, ii, 1'-'056-25'

UT code for WoS article

000408310600026

EID of the result in the Scopus database

2-s2.0-85021660800