Related papers: Numerical simulations of high-energy flows in accr…
We study the dependence of kHz quasi-periodic oscillation (QPO) frequency on accretion-related parameters in the ensemble of neutron star low-mass X-ray binaries. Based on the mass accretion rate, $\dot{M}$, and the magnetic field strength,…
We compare the determinations of the angular momentum of stellar mass black holes via the continuum and line methods with those from diskoseismology. The assumption being tested is that one of the QPOs (quasi-periodic oscillations) in each…
Quasi-periodic oscillations (QPOs) discovered in the decaying tails of giant flares of magnetars are believed to be torsional oscillations of neutron stars. These QPOs have a high potential to constrain properties of high-density matter. In…
Observations of the ultraviolet continuum of the X-ray binary system Her X-1/HZ Herculis with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope show quasiperiodic oscillations (QPOs) at frequencies of 8+/-2 and 43+/-2…
In all the microquasars with two hHz QPOs, the ratio of the frequencies is 3:2, supporting our suggestion that a non-linear resonance between two modes of oscillation in the accretion disk plays a role in exciting the observed modulations…
Quasi-periodic oscillations (QPOs) are very common in black hole accretion systems that are seen from the modulations in luminosity. Many supermassive black hole sources (e.g., RE J1034+396, 1H~0707-495, MCG-6-30-15, 1ES~1927+654,…
We conduct a parameter survey of neutron star accretion column simulations by solving the relativistic radiation MHD equations with opacities that account for strong magnetic fields and pair production. We study how column properties depend…
A three-dimensional numerical model for an accretion process investigation in the magnetosphere of a white dwarf in magnetic cataclysmic variables is developed. The model assumes that the white dwarf has a dipole magnetic field with its…
The presence of a kHz frequency in LMXBs has been expected from scaling laws, by analogy with the QPO phenomenon in HMXB X-ray pulsars. Interpretation of the two kHz frequencies, observed in accreting neutron stars, in terms of non-linear…
Optical quasi-periodic oscillations (QPOs) with periodicity around hundreds to thousands of days have been accepted as an efficient indicator for sub-pc binary black hole systems (BBHs) in broad line active galactic nuclei (BLAGN). However,…
Magneto-elastic oscillations of neutron stars are believed to explain observed quasi-periodic oscillations (QPOs) in the decaying tail of the giant flares of highly magnetized neutron stars (magnetars). Strong efforts of the theoretical…
Odd Radio Circles (ORCs) are a new class of distinct radio objects that has recently been discovered. The origin of these features is yet unclear because their peculiar properties are a challenge for our current understanding of…
It was pointed out by Paczynski (1987) that the X-ray luminosity of accreting neutron stars is very sensitive to the physical properties of the accretion flow close to the innermost stable circular orbit. The X-ray radiation is dominated by…
Given the peculiar and (in spite of many efforts) unexplained quasi-periodic oscillation (QPO) twin peak phenomena in accretion disc PSD observations, the present exploratory analytical article tries to inquire deeper into the relationship…
This paper provides a review of the kilohertz quasi-periodic oscillations in low-mass X-ray binaries recently discovered with NASA's Rossi X-ray Timing Explorer. It contains two tables that are up to date up to October 1st, 1997 with…
HST observations of some QSOs show a strong, abrupt increase in polarization at rest wavelength about 750 A, suggestive of a connection with the Lyman edge of hydrogen. Blaes and Agol (1996) have proposed an explanation in terms of stellar…
Quasi-periodic oscillations (QPOs), in particular, the ones with high frequencies, often observed in the power spectrum of black holes, are useful in understanding the nature of strong gravity since they are associated with the motion of…
We report on a ~37-ks XMM-Newton observation of the intermediate polar FO Aquarii, presenting X-ray and UV data from the EPIC and OM cameras. We find that the system has changed from its previously reported state of disc-overflow accretion…
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…
We present results of various types of numerical simulations of black hole accretion disks and find that those flows which are relatively non-dissipative and which contain accretion shocks are the best candidates so far. The power density…