Superspinning compact objects and models of highfrequency quasiperiodic oscillations observed in Galactic microquasars. II. Forced resonances
Abstract
In our previous work (Paper I) we applied several models of highfrequency quasiperiodic 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 superspinning 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 M × ν_{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 M × ν_{U}(a) that cannot be represented by single functions. Each of these five models is compatible with the expectation of a ≳ 1.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 November 2017
 DOI:
 10.1051/00046361/201730585
 arXiv:
 arXiv:1708.04300
 Bibcode:
 2017A&A...607A..69K
 Keywords:

 Xrays: binaries;
 black hole physics;
 accretion;
 accretion disks;
 Astrophysics  High Energy Astrophysical Phenomena
 EPrint:
 8 pages, 4 figures, accepted for publication in Astronomy &