Limits on thickness and efficiency of Polish doughnuts in application to the ULX sources

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F47813059%3A19240%2F16%3AN0000137" target="_blank" >RIV/47813059:19240/16:N0000137 - isvavai.cz</a>
Result on the web
<a href="http://www.aanda.org/articles/aa/abs/2016/03/aa27878-15/aa27878-15.html" target="_blank" >http://www.aanda.org/articles/aa/abs/2016/03/aa27878-15/aa27878-15.html</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1051/0004-6361/201527878" target="_blank" >10.1051/0004-6361/201527878</a>

Result language
angličtina
Original language name
Limits on thickness and efficiency of Polish doughnuts in application to the ULX sources
Original language description
Polish doughnuts (PDs) are geometrically thick disks that rotate with super-Keplerian velocities in their innermost parts, and whose long and narrow funnels along rotation axes collimate the emerging radiation into beams. In this paper we construct an extremal family of PDs that maximize both geometrical thickness and radiative efficiency. We then derive upper limits for these quantities and subsequently for the related ability to collimate radiation. PDs with such extreme properties may explain the observed properties of ultraluminous X-ray sources without the need for the black hole masses to exceed ~10 M⊙. However, we show that strong advective cooling, which is expected to be one of the dominant cooling mechanisms in accretion flows with super-Eddington accretion rates, tends to reduce the geometrical thickness and luminosity of PDs substantially. We also show that the beamed radiation emerging from the PD funnels corresponds to isotropic luminosities that obey $L_{col} ≈ 0.1 dot{M} c^2$ for $dot{M} >> dot{M}_{Edd}$, and not the familiar and well-known logarithmic relation, $L ~ ln dot{M}$.
Czech name
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Czech description
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Type
J<sub>x</sub> - Unclassified - Peer-reviewed scientific article (Jimp, Jsc and Jost)
CEP classification
BN - Astronomy and celestial mechanics, astrophysics
OECD FORD branch
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Project
<a href="/en/project/EE2.3.20.0071" target="_blank" >EE2.3.20.0071: Supporting Integration with the International Theoretical and Observational Research Network in Relativistic Astrophysics of Compact Objects</a><br>
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year
2016
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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