Journal Article

Weighing the black holes in ultraluminous X-ray sources through timing

P. Casella, G. Ponti, A. Patruno, T. Belloni, G. Miniutti and L. Zampieri

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 387, issue 4, pages 1707-1711
Published in print July 2008 | ISSN: 0035-8711
Published online July 2008 | e-ISSN: 1365-2966 | DOI:
Weighing the black holes in ultraluminous X-ray sources through timing

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We describe a new method to estimate the mass of black holes in Ultraluminous X-ray Sources (ULXs). The method is based on the recently discovered ‘variability plane’, populated by Galactic stellar-mass black-hole candidates (BHCs) and supermassive active galactic nuclei (AGNs), in the parameter space defined by the black-hole mass, accretion rate and characteristic frequency. We apply this method to the two ULXs from which low-frequency quasi-periodic oscillations have been discovered, M82 X-1 and NGC 5408 X-1. For both sources we obtain a black-hole mass in the range 100–1300 M, thus providing evidence for these two sources to host an intermediate-mass black hole.

Keywords: accretion, accretion discs; black hole physics; X-rays: binaries; X-rays: individual: M82 X-1; X-rays: individual: NGC 5408 X-1

Journal Article.  3945 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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