Ultraluminous X-ray sources with flat-topped noise and QPO

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F19%3A00517314" target="_blank" >RIV/67985815:_____/19:00517314 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.1093/mnras/stz1027" target="_blank" >https://doi.org/10.1093/mnras/stz1027</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1093/mnras/stz1027" target="_blank" >10.1093/mnras/stz1027</a>

Result language

angličtina

Original language name

Ultraluminous X-ray sources with flat-topped noise and QPO

Original language description

We analysed the X-ray power density spectra of five ultraluminous X-ray sources (ULXs) NGC5408 X-1, NGC6946 X-1, M82 X-1, NGC1313 X-1, and IC 342 X-1 that are the only ULXs that display both flat-topped noise (FTN) and quasi-periodic oscillations (QPOs). We studied the QPO frequencies, fractional root-mean-square (rms) variability, X-ray luminosity, and spectral hardness. We found that the level of FTN is anticorrelated with the QPO frequency. As the frequency of the QPO and brightness of the sources increase, their fractional variability decreases. We propose a simple interpretation using the spherization radius, viscosity time, and a-parameter as basic properties of these systems. The main physical driver of the observed variability is the mass accretion rate that varies greater than or similar to 3 between different observations of the same source. As the accretion rate decreases the spherization radius reduces and the FTN plus the QPO move towards higher frequencies, resulting in a decrease of the fractional rms variability. We also propose that in all ULXs when the accretion rate is low enough (but still super-Eddington) the QPO and FTN disappear. Assuming that the maximum X-ray luminosity depends only on the black hole (BH) mass and not on the accretion rate (not considering the effects of either the inclination of the super-Eddington disc or geometrical beaming of radiation), we estimate that all the ULXs have about similar BH masses, with the exception of M82 X-1, which might be 10 times more massive.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

<a href="/en/project/GA18-00533S" target="_blank" >GA18-00533S: Reverberation from Black Hole accretion discs</a><br>

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2019

Confidentiality

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

Name of the periodical

Monthly Notices of the Royal Astronomical Society

ISSN

1365-2966

e-ISSN

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Volume of the periodical

486

Issue of the periodical within the volume

2

Country of publishing house

GB - UNITED KINGDOM

Number of pages

14

Pages from-to

2766-2779

UT code for WoS article

000474899400100

EID of the result in the Scopus database

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