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

Kód výsledku v 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>

Výsledek na webu

<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>

Jazyk výsledku

angličtina

Název v původním jazyce

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

Popis výsledku v původním jazyce

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, $L ~ ln dot{M}$.

Název v anglickém jazyce

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

Popis výsledku anglicky

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, $L ~ ln dot{M}$.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

BN - Astronomie a nebeská mechanika, astrofyzika

OECD FORD obor

—

Projekt

<a href="/cs/project/EE2.3.20.0071" target="_blank" >EE2.3.20.0071: Podpora zapojení do mezinárodních sítí teoretického a observačního výzkumu v oblasti relativistické astrofyziky kompaktních objektů</a><br>

Návaznosti

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

Rok uplatnění

2016

Kód důvěrnosti údajů

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

Název periodika

Astronomy and Astrophysics

ISSN

0004-6361

e-ISSN

—

Svazek periodika

587

Číslo periodika v rámci svazku

March

Stát vydavatele periodika

FR - Francouzská republika

Počet stran výsledku

7

Strana od-do

'A38-1'-'A38-7'

Kód UT WoS článku

000371589800049

EID výsledku v databázi Scopus

2-s2.0-84958279987