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

    Zdeněk Stuchlík · Prosinec 01, 2014 · Fyzika · 0 comments
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    Publication date: Dec 2014

    Abstract:
    We have previously applied several models of high-frequency
    quasi-periodic oscillations (HF QPOs) to estimate the spin of the
    central Kerr black hole in the three Galactic microquasars, GRS
    1915+105, GRO J1655-40, and XTE J1550-564. Here we explore the
    alternative possibility that the central compact body is a
    super-spinning object (or a naked singularity) with the external
    space-time described by Kerr geometry with a dimensionless spin
    parameter a ≡ cJ/GM2> 1. We calculate the relevant
    spin intervals for a subset of HF QPO models considered in the previous
    study. Our analysis indicates that for all but one of the considered
    models there exists at least one interval of a> 1 that is compatible
    with constraints given by the ranges of the central compact object mass
    independently estimated for the three sources. For most of the models,
    the inferred values of a are several times higher than the extreme Kerr
    black hole value a = 1. These values may be too high since the spin of
    superspinars is often assumed to rapidly decrease due to accretion when
    a ≫ 1. In this context, we conclude that only the epicyclic and the
    Keplerian resonance model provides estimates that are compatible with
    the expectation of just a small deviation from a = 1.

    Authors:
    Kotrlová, Andrea; Török, Gabriel; Šrámková, Eva; Stuchlík, Zdeněk;

    http://adsabs.harvard.edu/abs/2014A%26A…572A..79K

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