J 2017

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

STUCHLÍK, Zdeněk, Jan SCHEE, Bobir TOSHMATOV, Jan HLADÍK, Jan NOVOTNÝ et. al.

Basic information

Original name

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

Authors

STUCHLÍK, Zdeněk (203 Czech Republic, guarantor, belonging to the institution), Jan SCHEE (203 Czech Republic, belonging to the institution), Bobir TOSHMATOV (860 Uzbekistan, belonging to the institution), Jan HLADÍK (203 Czech Republic, belonging to the institution) and Jan NOVOTNÝ (203 Czech Republic, belonging to the institution)

Edition

Journal of Cosmology and Astroparticle Physics, 2017, 1475-7516

Other information

Language

English

Type of outcome

Článek v odborném periodiku

Field of Study

10308 Astronomy

Country of publisher

United Kingdom of Great Britain and Northern Ireland

Confidentiality degree

není předmětem státního či obchodního tajemství

RIV identification code

RIV/47813059:19240/17:A0000015

Organization

Filozoficko-přírodovědecká fakulta – Slezská univerzita v Opavě – Repository

UT WoS

000408310600026

Keywords in English

gravitational waves / theory; star formation; stars

Tags

International impact, Reviewed

Links

GB14-37086G, research and development project.
Změněno: 5/4/2018 17:17, Jan Hladík

Abstract

V originále

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 > 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 > 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 >= 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.