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SUMMARY:Oscillations of non-slender tori in the Hartle-Thorne geometry
DTSTART;VALUE=DATE-TIME:20201021T115000Z
DTEND;VALUE=DATE-TIME:20201021T120000Z
DTSTAMP;VALUE=DATE-TIME:20231205T014528Z
UID:indico-contribution-8-49@indico.slu.cz
DESCRIPTION:Speakers: Monika Matuszková ()\nWe examine the influence of t
he quadrupole moment of slowly rotating neutron stars on the oscillations
of non-slender accretion tori. We assume a perfect fluid\, polytropic\, co
nstant speciﬁc angular momentum\, non-selfgravitating torus and analytic
ally calculate formulas for the oscillation frequencies. So far\, these h
ave only been studied in the Kerr geometry. We apply known methods for exa
mining the properties of radial and vertical axisymmetric and non-axisymme
tric (m = -1) epicyclic modes of oscillating accretion tori in the Hartle-
Thorne geometry. Our results are valid within the accuracy of up to second
order in the angular momentum of the neutron star and the first order in
its quadrupole moment. These can be used to study the properties of relati
vistic compact objects through the low-mass X-ray binaries phenomenon comm
only known as the twin-peak quasi-periodic oscillations.\n\nhttps://indico
.slu.cz/event/4/contributions/49/
LOCATION:
URL:https://indico.slu.cz/event/4/contributions/49/
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SUMMARY:Oscillation modes of thick accretion disks using finite-elements c
alculations
DTSTART;VALUE=DATE-TIME:20201021T112500Z
DTEND;VALUE=DATE-TIME:20201021T115000Z
DTSTAMP;VALUE=DATE-TIME:20231205T014528Z
UID:indico-contribution-8-40@indico.slu.cz
DESCRIPTION:Speakers: Jiri Horak (Astronomical Institute ASCR\, Prague)\nW
e will present results for oscillation modes of thick accretion tori in Ke
rr spacetime using finite-element numerical method. We will derive relativ
istic version of the Papaloizou-Pringle equation for disks with general an
gular momentum distribution. Then we focus on the case of constant angular
momentum tori and compare our results with those previously found by anal
ytic perturbation methods.\n\nhttps://indico.slu.cz/event/4/contributions/
40/
LOCATION:
URL:https://indico.slu.cz/event/4/contributions/40/
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SUMMARY:X-ray timing and mass of accreting compact objects
DTSTART;VALUE=DATE-TIME:20201021T120000Z
DTEND;VALUE=DATE-TIME:20201021T122500Z
DTSTAMP;VALUE=DATE-TIME:20231205T014528Z
UID:indico-contribution-8-5@indico.slu.cz
DESCRIPTION:Speakers: Gabriel Török (Institute of Physics\, Silesian Uni
versity in Opava)\nWe explore the influence of non-geodesic pressure force
s that are present in an accretion disk on the frequencies of its axisymme
tric and non-axisymmetric epicyclic oscillation modes. We discuss its impl
ications for models of high-frequency quasi-periodic oscillations (QPOs) t
hat have been observed in the X-ray flux of accreting black holes (BHs) an
d neutron stars (NSs). In particular\, we discuss the implications for a m
odel recently proposed in the context of neutron NS QPOs as a disk-oscilla
tion-based modification of the relativistic precession model. This model p
rovides overall better fits of the NS data and predicts more realistic val
ues of the NS mass compared to the relativistic precession model. It also
implies a significantly higher upper limit on the microquasar's BH spin.
We show that there is an analytic formula that well reproduce the models p
redictions on the QPO frequencies. Our simple formula may be used along wi
th the observed QPO frequencies to estimate the mass and spin of compact o
bjects.\n\nhttps://indico.slu.cz/event/4/contributions/5/
LOCATION:
URL:https://indico.slu.cz/event/4/contributions/5/
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