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    Confronting the models of 3:2 quasiperiodic oscillations with the rapid spin of the microquasar GRS 1915+105

    Zdeněk Stuchlík · 01 července, 2011 · Fyzika · 0 comments
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    Publication date: Jul 2011

    Abstract:
    Spectral fitting of the spin a ≡ cJ/GM2 in the
    microquasar GRS 1915+105 estimate values higher than a = 0.98. However,
    there are certain doubts about this (nearly) extremal number. Confirming
    a high value of a > 0.9 would have significant concequences for the
    theory of high-frequency quasiperiodic oscillations (HF QPOs). Here we
    discuss its possible implications assuming several commonly used orbital
    models of 3:2 HF QPOs. We show that the estimate of a > 0.9 is almost
    inconsistent with two hot-spot (relativistic precession and tidal
    disruption) models and the warped disc resonance model. In contrast, we
    demonstrate that the epicyclic resonance and discoseismic models
    assuming the c- and g-modes are favoured. We extend our discussion to
    another two microquasars that display the 3:2 HF QPOs. The frequencies
    of these QPOs scale roughly inversely to the microquasar masses, and the
    differences in the individual spins, such as a = 0.9 compared to a =
    0.7, represent a generic problem for most of the discussed geodesic 3:2
    QPO models. To explain the observations of all the three microquasars by
    one unique mechanism, the models would have to accommodate very large
    non-geodesic corrections.

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

    http://adsabs.harvard.edu/abs/2011A%26A…531A..59T

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