2017A&A...607A..69K -
Astronomy and Astrophysics, volume 607A, 69-69 (2017/11-1)
Super-spinning compact objects and models of high-frequency quasi-periodic oscillations observed in Galactic microquasars. II. Forced resonances.
KOTRLOVA A., SRAMKOVA E., TOROK G., STUCHLIK Z. and GOLUCHOVA K.
Abstract (from CDS):
In our previous work (Paper I,
2014A&A...572A..79K ) we applied several models of high-frequency quasi-periodic oscillations (HF QPOs) to estimate the spin of the central compact object in three Galactic microquasars assuming the possibility that the central compact body is a super-spinning object (or a naked singularity) with external spacetime described by Kerr geometry with a dimensionless spin parameter a∼cJ/GM
2>1. Here we extend our consideration, and in a consistent way investigate implications of a set of ten resonance models so far discussed only in the context of a<1. The same physical arguments as in Paper I are applied to these models, i.e. only a small deviation of the spin estimate from a=1, a≥1, is assumed for a favoured model. For five of these models that involve Keplerian and radial epicyclic oscillations we find the existence of a unique specific QPO excitation radius. Consequently, there is a simple behaviour of dimensionless frequency Mxν
U(a) represented by a single continuous function having solely one maximum close to a≥1. Only one of these models is compatible with the expectation of a≥1. The other five models that involve the radial and vertical epicyclic oscillations imply the existence of multiple resonant radii. This signifies a more complicated behaviour of Mxν
U(a) that cannot be represented by single functions. Each of these five models is compatible with the expectation of a≥1.
Abstract Copyright:
© ESO, 2017
Journal keyword(s):
X-rays: binaries - black hole physics - accretion, accretion disks - accretion, accretion disks
Simbad objects:
4
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