publications    
 
 
INFO PEOPLE NEWS COOPERATION ACTIVITIES PARALAB RELATIVITY ONLINE
 
 
 
 
czech english
 
Magion
 
PUBLICATIONS
CONFERENCES
 
 
External links
Ministry of Education
FPF SLU Opava
UF FPF
NASA ADS
astro-ph
gr-qc
ISI Web of Knowledge
Scopus



ADMIN
 
 
 

Reports on present stage of some projects realized on Blade-center within the framework of cooperation between MSM 4781305903 and CTA.

MODELLING X-RAY POWER SPECTRA OF HOT-SPOTS



MODELLING HIGH FREQUENCY QPOs AND EQUATIONS OF STATE

Inserted: 27.2.2009

Relating X-ray timing observations of NS LMXBs to Equations of state

Within the work on Relativity Online we tested application of a genetic algorithm (GA) on relating the QPO models to neutron star equations of state. Using GA we select the acceptable EOS from 27 types of the Skyrmion EOS for the source 4U 1636-53 and QPO interpretation based on relativistic-precession-like family of relations.



The results are yet preliminary as the relations for QPO frequencies contain an arbitrary therm describing non-geodesic effects. Full info
Inserted: 24.7.2008

Mass and angular momentum of the neutron-star X-ray binary 4U 1636-53





The kHz quasiperiodic oscillations (QPOs) observed in low-mass X-ray neutron star binaries are most likely connected to the orbital motion in the accretion disc. Assuming the neutron star external spacetime to be described by the Hartle-Thorne metric, we search in the case of the atoll source 4U 1636-53 for a frequency relation matching the observed datapoints. We calculated several frequency relations in the Hartle--Thorne metric for the range of the mass between one and three solar masses, the internal angular momentum j = 0-0.5 and a physically meaningful quadrupole momentum q with a step equivalent to the thousand points in all three quantities, i.e., several 3-dimensional maps each having 10^9 points. Then we applied the Levenberg-Marquardt nonlinear least
squares method.



We have identified a suitable class of frequency relations well fitting the observed data. The discussed geodesic relations provide fits which are in good qualitative agreement with general trend observed in the neutron star kHz QPO data. Nevertheless no one of this relations provides really good fits (we checked for the other five atoll sources, that trends are same as for 4U 1636-53). In addition the best fits requires rather unrealistic values of mass and angular momentum with respect to the present knowledge of the neutron star equation of state. To check whether some non geodesic influence can resolve the problem above we consider the assumption that the effective frequency of radial
oscillations may be lowered, e.g., by the hotspots interaction with the accretion disk or with the neutron star magnetic field.
Full info
Inserted: 7.5.2007

Administrator of our BLADE server has became Mgr.Milan Uhlár.

Inserted: 27.7.2006

We construct a centre for parralel programming and preparations for parallel computer selection procedure proceed; during those preparations we have addresed following companies: IBM, SGI, HP and SUN. In June and July we tested IBM Blade Server (6 CPU) at Opava, in the frame of tests simulation of optical effects during observers fall into a black hole was developed. Currently we are testing SGI computer.

Ilustrations of optical effects in the vicinity of black hole, produced during tests of IBM computer.
Inserted: 5.9.2005