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

Maciej Wielgus , W. Yan , J. P. Lasota , M. Abramowicz

Abstract

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 Lcol ≈ 0.1Ṁc2 for Ṁ ≫ ṀEdd, and not the familiar and well-known logarithmic relation, L ~ lnṀ.
Author Maciej Wielgus IMiF
Maciej Wielgus,,
- The Institute of Micromechanics and Photonics
, W. Yan
W. Yan,,
-
, J. P. Lasota
J. P. Lasota,,
-
, M. Abramowicz
M. Abramowicz,,
-
Journal seriesAstronomy & Astrophysics, ISSN 0004-6361
Issue year2016
Vol587
Pages1512.00749-1 - 1512.00749-7
Publication size in sheets0.3
Keywords in Polishakrecja, dyski akrecyjne, jety, czarne dziury, fizyka czarnych dziur, gwiazdy neutronowe
Keywords in Englishaccretion, accretion disks, jets, black holes, black hole physics, neutron stars
Abstract in PolishBadamy własności analitycznego modelu grubego dysku akrecyjnego („Polski pączek”) z dodatkowym założeniem na temat adwekcji. Wykazujemy, że straty adwekcyjne zmniejszają istotnie grubość dysku. Dyskutujemy maksymalną efektywność, grubość, i skolimowaną jasność adwekcyjnych grubych dysków.
DOIDOI:10.1051/0004-6361/201527878
URL http://www.aanda.org/articles/aa/pdf/forth/aa27878-15.pdf
Languageen angielski
Score (nominal)35
ScoreMinisterial score [Punktacja MNiSW] = 35.0, 28-11-2017, ArticleFromJournal
Ministerial score (2013-2016) [Punktacja MNiSW (2013-2016)] = 35.0, 28-11-2017, ArticleFromJournal
Publication indicators WoS Impact Factor [Impact Factor WoS]: 2014 = 4.378 (2) - 2014=4.158 (5)
Citation count*3 (2018-06-19)
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* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.
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