Related papers: Confronting models for the high-frequency QPOs wit…
In the context of black hole spin in X-ray binaries, we propose that certain type of quasi-period oscillations (QPOs) observed in the light curves of black hole binaries (BHBs) are produced by X-ray modulation at the precession frequency of…
The black hole mass and spin estimates assuming various specific models of the 3:2 high frequency quasi-periodic oscillations (HF QPOs) have been carried out in Torok et al. (2005, 2011). Here we briefly summarize some current points.…
The high-frequency quasi-periodic oscillations (HF QPOs) that appear in the X-ray fluxes of low-mass X-ray binaries remain an unexplained phenomenon. Among other ideas, it has been suggested that a non-linear resonance between two…
In the resonance model, high-frequency quasi-periodic oscillations (QPOs) are supposed to be a consequence of nonlinear resonance between modes of oscillations occurring within the innermost parts of an accretion disk. Several models with a…
Using the two main XTE J1550-564 outbursts (1998-99 and 2000) we gathered about 30 observations with confirmed detections of HFQPOs. While this is a small sample it is enough to start looking at the generic properties of these oscillations,…
Observations with RXTE (Rossi X-ray Timing Explorer) revealed the presence of High Frequency Quasi-Periodic Oscillations (HFQPOs) of the X-ray flux from several accreting stellar mass Black Holes. HFQPOs (and their counterparts at lower…
Quasi-periodic oscillation (QPO) detected in the X-ray radiation of black hole X-ray binaries (BHXBs) is thought to originate from dynamical processes in the close vicinity of the black holes (BHs), and thus carries important physical…
Astrophysical black hole candidates are thought to be the Kerr black hole predicted by General Relativity. In order to confirm the Kerr-nature of these objects, we need to probe the geometry of the space-time around them and see if the…
High-frequency quasiperiodic oscillations of the X-ray flux comming from black-hole binaries have the potential to provide precise estimates of the mass and the spin of the central black hole, if an adequate model for them was available.…
Future very-large-area X-ray instruments (for which the effective area is larger than $>3$m$^2$) will be able to measure the frequencies of quasi-periodic oscillations~(QPOs) observed in the X-ray flux from accreting compact objects with…
We present the results of timing analysis of the low-frequency Quasi-Periodic Oscillation (QPO) in the Rossi X-Ray Timing Explorer data of the black hole binary XTE J1550--564 during its 1998 outburst. The QPO frequency is observed to vary…
We compile observations of high-frequency quasi-periodic oscillations (QPOs) around black holes, both stellar and supermassive, and compare their positions in the parameter space of black hole mass, spin, and oscillation frequency. We find…
Black hole X-ray binaries (BHXRBs) display a wide range of variability phenomena, from long duration spectral state changes to short-term broadband variability and quasi-periodic oscillations (QPOs). A particularly puzzling aspect is the…
In this study, the behavior of high-frequency quasi-periodic oscillations (QPOs) is investigated around a Kerr black hole immersed in a uniform Bertotti-Robinson magnetic field. The motion of the test particle is analyzed by determining the…
Many Galactic black hole and neutron star sources in low X-ray mass binaries show QPOs (quasi periodic oscillations) in their observed X-ray fluxes, i.e. peaks in the Fourier variability power spectra. Pairs of twin peaks are observed, and…
High frequency (millisecond) quasi-periodic oscillations (HF QPOs) are observed in the X-ray power-density spectra of several microquasars and low mass X-ray binaries. Two distinct QPO peaks, so-called twin peak QPOs, are often detected…
In previous papers we proposed a model that high-frequency quasi-periodic oscillations (QPOs) observed in black-hole and neutron-star X-ray binaries are disk oscillations (inertial-acoustic and/or g-mode oscillations) resonantly excited on…
Type-C QPOs in X-ray binaries have been often interpreted as a consequence of relativistic Lense-Thirring precession around a spinning black hole and they potentially offer a way to measure black hole spins and masses. The connection…
We show in this Letter that relativistic dragging of inertial frames around fast rotating collapsed stars is substantial and can give rise to observable effects. We apply this to the kHz quasi periodic oscillations (QPOs) sources, low mass…
Low mass x-ray binaries (LMXBs), with either a neutron star (NS) or a black hole, show in their power spectra quasiperiodic oscillations (QPOs). Those at highest frequencies show up in pairs and are named twin peak high frequency QPOs (HF…