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    Black Holes Admitting Strong Resonant Phenomena

    Zdeněk Stuchlík · Prosinec 01, 2008 · Fyzika · 0 comments
    0

    Publication date: Dec 2008

    Abstract:
    High-frequency twin peak quasiperiodic oscillations (QPOs) are observed
    in four microquasars, i.e., Galactic black hole binary systems, with
    frequency ratio very close to 3:2. In the microquasar GRS 1915+105 the
    structure of QPOs exhibits additional frequencies and more than two
    frequencies are observed in the Galaxy nuclei Sgr A* or in some
    extragalactic sources (NGC 4051, MCG-6-30-15 and NGC 5408 X-1). The
    observed QPOs can be explained by a variety of the orbital resonance
    model versions assuming resonance of oscillations with the Keplerian
    frequency νK or the vertical epicyclic frequency
    νθ, and the radial epicyclic frequency
    νr, or some combinations of these frequencies. Generally,
    different resonances could arise at different radii of an accretion
    disk. However, we have shown that for special values of dimensionless
    black hole spin a strong resonant phenomena could occur when different
    resonances can be excited at the same radius, as cooperative phenomena
    between the resonances may work in such situations. The special values
    of a are determined for triple frequency ratio sets
    νK:νθ:νr=s:t:u with
    s,t,u being small integers. The most promising example of such a special
    situation arises for black holes with extraordinary resonant spin
    a=0.983 at the radius r=2.395 M, where
    νK:νθ:νr=3:2:1. We also
    predict that when combinations of the orbital frequencies are allowed,
    QPOs with four frequency ratio set 4:3:2:1 could be observed in the
    field of black holes with a=0.866,0.882 and 0.962. Assuming the
    extraordinary resonant spin a=0.983 in Sgr A*, its QPOs with observed
    frequency ratio ≍3:2:1 imply the black hole mass in the interval
    4.3×106 Msolar< M<
    5.4×106 Msolar, in agreement with estimates
    given by other, independent, observations.

    Authors:
    Stuchlík, Z.; Kotrlová, A.; G. Török;

    http://adsabs.harvard.edu/abs/2008AcA….58..441S

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