|
ИСТИНА |
Войти в систему Регистрация |
ИПМех РАН |
||
Ultraluminous X-ray sources with flat-topped noise and QPOстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 14 августа 2019 г.
- Авторы: Atapin Kirill, Fabrika Sergei, Caballero-García Maria D.
- Журнал: Monthly Notices of the Royal Astronomical Society
- Том: 486
- Номер: 2
- Год издания: 2019
- Издательство: Oxford Journals, Oxford University Press
- Местоположение издательства: Oxford, UK, England
- Первая страница: 2766
- Последняя страница: 2779
- DOI: 10.1093/mnras/stz1027
- Аннотация: We analysed the X-ray power density spectra of five ultraluminous X-ray sources (ULXs) NGC 5408 X-1, NGC 6946 X-1, M 82 X-1, NGC 1313 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 α-parameter as basic properties of these systems. The main physical driver of the observed variability is the mass accretion rate that varies ≳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 M 82 X-1, which might be 10 times more massive.
- Добавил в систему: Атапин Кирилл Евгеньевич