paper

Super-spinning compact objects and models of high-frequency quasi-periodic oscillations observed in Galactic microquasars. II. Forced resonances

arXiv:1708.04300 · doi:10.1051/0004-6361/201730585

Abstract

In our previous work (Paper I) 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 . 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 . The same physical arguments as in Paper I are applied to these models, i.e. only a small deviation of the spin estimate from , , 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 represented by a single continuous function having solely one maximum close to . Only one of these models is compatible with the expectation of . 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 that cannot be represented by single functions. Each of these five models is compatible with the expectation of .

8 pages, 4 figures, accepted for publication in Astronomy & Astrophysics

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