TY - JOUR
T1 - High-frequency X-ray variability as a mass estimator of stellar and supermassive black holes
AU - Gierliński, Marek
AU - Nikołajuk, Marek
AU - Czerny, Boena
PY - 2008/1/11
Y1 - 2008/1/11
N2 - There is increasing evidence that supermassive black holes in active galactic nuclei (AGN) are scaled-up versions of Galactic black holes. We show that the amplitude of high-frequency X-ray variability in the hard spectral state is inversely proportional to the black hole mass over eight orders of magnitude. We have analysed all available hard-state data from RXTE of seven Galactic black holes. Their power density spectra change dramatically from observation to observation, except for the high-frequency (≳10 Hz) tail, which seems to have a universal shape, roughly represented by a power law of index -2. The amplitude of the tail, CM (extrapolated to 1 Hz), remains approximately constant for a given source, regardless of the luminosity, unlike the break or quasi-periodic oscillation frequencies, which are usually strongly correlated with luminosity. Comparison with a moderate-luminosity sample of AGN shows that the amplitude of the tail is a simple function of black hole mass, CM = C/M, where C ≈ 1.25 M⊙ Hz -1. This makes CM a robust estimator of the black hole mass which is easy to apply to low- to moderate-luminosity supermassive black holes. The high-frequency tail with its universal shape is an invariant feature of a black hole and, possibly, an imprint of the last stable orbit.
AB - There is increasing evidence that supermassive black holes in active galactic nuclei (AGN) are scaled-up versions of Galactic black holes. We show that the amplitude of high-frequency X-ray variability in the hard spectral state is inversely proportional to the black hole mass over eight orders of magnitude. We have analysed all available hard-state data from RXTE of seven Galactic black holes. Their power density spectra change dramatically from observation to observation, except for the high-frequency (≳10 Hz) tail, which seems to have a universal shape, roughly represented by a power law of index -2. The amplitude of the tail, CM (extrapolated to 1 Hz), remains approximately constant for a given source, regardless of the luminosity, unlike the break or quasi-periodic oscillation frequencies, which are usually strongly correlated with luminosity. Comparison with a moderate-luminosity sample of AGN shows that the amplitude of the tail is a simple function of black hole mass, CM = C/M, where C ≈ 1.25 M⊙ Hz -1. This makes CM a robust estimator of the black hole mass which is easy to apply to low- to moderate-luminosity supermassive black holes. The high-frequency tail with its universal shape is an invariant feature of a black hole and, possibly, an imprint of the last stable orbit.
KW - Accretion, accretion discs
KW - Galaxies: active
KW - X-rays: binaries
UR - http://www.scopus.com/inward/record.url?scp=37848998789&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2966.2007.12584.x
DO - 10.1111/j.1365-2966.2007.12584.x
M3 - Article
AN - SCOPUS:37848998789
VL - 383
SP - 741
EP - 749
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 2
ER -