Models of high-frequency quasi-periodic oscillations and black hole spin estimates in Galactic microquasars. (arXiv:2008.12963v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Kotrlova_A/0/1/0/all/0/1">Andrea Kotrlová</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sramkova_E/0/1/0/all/0/1">Eva Šrámková</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Torok_G/0/1/0/all/0/1">Gabriel Török</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Goluchova_K/0/1/0/all/0/1">Kateřina Goluchová</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jiri_H/0/1/0/all/0/1">Horák Jiří</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Straub_O/0/1/0/all/0/1">Odele Straub</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lancova_D/0/1/0/all/0/1">Debora Lančová</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stuchlik_Z/0/1/0/all/0/1">Zdeňek Stuchlík</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Abramowicz_M/0/1/0/all/0/1">Marek Abramowicz</a>
We explore the influence of non-geodesic pressure forces that are present in
an accretion disk on the frequencies of its axisymmetric and non-axisymmetric
epicyclic oscillation modes. {We discuss its implications for models of
high-frequency quasi-periodic oscillations (QPOs) that have been observed in
the X-ray flux of accreting black holes (BHs) in the three Galactic
microquasars, GRS 1915+105, GRO J1655$-$40 and XTE J1550$-$564. We focus on
previously considered QPO models that deal with low azimuthal number epicyclic
modes, $lvert m rvert leq 2$, and outline the consequences for the
estimations of BH spin, $ain[0,1]$.} For four out of six examined models, we
find only small, rather insignificant changes compared to the geodesic case.
For the other two models, on the other hand, there is a fair increase of the
estimated upper limit on the spin. Regarding the QPO model’s falsifiability, we
find that one particular model from the examined set is incompatible with the
data. If the microquasar’s spectral spin estimates that point to $a>0.65$ were
fully confirmed, two more QPO models would be ruled out. Moreover, if two very
different values of the spin, such as $aapprox 0.65$ in GRO J1655$-$40 vs.
$aapprox 1$ in GRS 1915+105, were confirmed, all the models except one would
remain unsupported by our results. Finally, we discuss the implications for a
model recently proposed in the context of neutron star (NS) QPOs as a
disk-oscillation-based modification of the relativistic precession model. This
model provides overall better fits of the NS data and predicts more realistic
values of the NS mass compared to the relativistic precession model. We
conclude that it also implies a significantly higher upper limit on the
microquasar’s BH spin ($asim 0.75$ vs. $asim 0.55$).
We explore the influence of non-geodesic pressure forces that are present in
an accretion disk on the frequencies of its axisymmetric and non-axisymmetric
epicyclic oscillation modes. {We discuss its implications for models of
high-frequency quasi-periodic oscillations (QPOs) that have been observed in
the X-ray flux of accreting black holes (BHs) in the three Galactic
microquasars, GRS 1915+105, GRO J1655$-$40 and XTE J1550$-$564. We focus on
previously considered QPO models that deal with low azimuthal number epicyclic
modes, $lvert m rvert leq 2$, and outline the consequences for the
estimations of BH spin, $ain[0,1]$.} For four out of six examined models, we
find only small, rather insignificant changes compared to the geodesic case.
For the other two models, on the other hand, there is a fair increase of the
estimated upper limit on the spin. Regarding the QPO model’s falsifiability, we
find that one particular model from the examined set is incompatible with the
data. If the microquasar’s spectral spin estimates that point to $a>0.65$ were
fully confirmed, two more QPO models would be ruled out. Moreover, if two very
different values of the spin, such as $aapprox 0.65$ in GRO J1655$-$40 vs.
$aapprox 1$ in GRS 1915+105, were confirmed, all the models except one would
remain unsupported by our results. Finally, we discuss the implications for a
model recently proposed in the context of neutron star (NS) QPOs as a
disk-oscillation-based modification of the relativistic precession model. This
model provides overall better fits of the NS data and predicts more realistic
values of the NS mass compared to the relativistic precession model. We
conclude that it also implies a significantly higher upper limit on the
microquasar’s BH spin ($asim 0.75$ vs. $asim 0.55$).
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