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@article{29879, author = {Stuchlík, Zdeněk and Schee, Jan and Toshmatov, Bobir and Hladík, Jan and Novotný, Jan}, article_number = {6}, doi = {http://dx.doi.org/10.1088/1475-7516/2017/06/056}, keywords = {gravitational waves / theory; star formation; stars}, language = {eng}, issn = {1475-7516}, journal = {Journal of Cosmology and Astroparticle Physics}, title = {Gravitational instability of polytropic spheres containing region of trapped null geodesics: a possible explanation of central supermassive black holes in galactic halos}, url = {http://iopscience.iop.org/article/10.1088/1475-7516/2017/06/056/meta}, volume = {neuveden}, year = {2017} }
TY - JOUR ID - 29879 AU - Stuchlík, Zdeněk - Schee, Jan - Toshmatov, Bobir - Hladík, Jan - Novotný, Jan PY - 2017 TI - Gravitational instability of polytropic spheres containing region of trapped null geodesics: a possible explanation of central supermassive black holes in galactic halos JF - Journal of Cosmology and Astroparticle Physics VL - neuveden IS - 6 SP - „056- i, ii, 1“-„056-25“ EP - „056- i, ii, 1“-„056-25“ SN - 14757516 KW - gravitational waves / theory KW - star formation KW - stars UR - http://iopscience.iop.org/article/10.1088/1475-7516/2017/06/056/meta L2 - http://iopscience.iop.org/article/10.1088/1475-7516/2017/06/056/meta N2 - 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. ER -
STUCHLÍK, Zdeněk, Jan SCHEE, Bobir TOSHMATOV, Jan HLADÍK and Jan NOVOTNÝ. Gravitational instability of polytropic spheres containing region of trapped null geodesics: a possible explanation of central supermassive black holes in galactic halos. \textit{Journal of Cosmology and Astroparticle Physics}. 2017, neuveden, No~6, p.~„056- i, ii, 1“-„056-25“, 27 pp. ISSN~1475-7516. Available from: https://dx.doi.org/10.1088/1475-7516/2017/06/056.
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