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

Kód výsledku v 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>

Výsledek na webu

<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>

Jazyk výsledku

angličtina

Název v původním jazyce

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

Popis výsledku v původním jazyce

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.

Název v anglickém jazyce

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

Popis výsledku anglicky

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.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

<a href="/cs/project/GA18-00533S" target="_blank" >GA18-00533S: Reverberace akrečních disků černých děr</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2019

Kód důvěrnosti údajů

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

Název periodika

Monthly Notices of the Royal Astronomical Society

ISSN

1365-2966

e-ISSN

—

Svazek periodika

486

Číslo periodika v rámci svazku

2

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

14

Strana od-do

2766-2779

Kód UT WoS článku

000474899400100

EID výsledku v databázi Scopus

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