相关论文: Quasi-periodic oscillations from post-shock accret…

We report the discovery of the correlated optical/X-ray low-frequency quasi-periodic oscillations (QPOs) in black hole binary SWIFT J1753.5-0127. The phase lag between two light-curves at the QPO frequency is close to zero. This result puts…

In this work, we probe the well known thermodynamic phase structure of black hole through the lens of its quasi-periodic oscillations (QPOs). Can QPOs be influenced by black hole phase transitions? Do they carry any signature of such…

We present recent results of 3D magnetohydrodynamic simulations of neutron stars with small misalignment angles, as regards the features in lightcurves produced by regular movements of the hot spots during accretion onto the star. In…

The origin of quasi-periodic oscillations (QPOs) in black hole accretion flow remains uncertain, particularly regarding the role of magnetic field configurations in shaping disk structure and variability signatures. We investigate this…

Quasi-periodic oscillations (QPOs) are coherent peaks of variability power observed in the X-ray power spectra (PSDs) of stellar mass X-ray binaries (XRBs). A scale invariance of the accretion process implies they should be present in the…

We present relativistic, radiation magnetohydrodynamic simulations of supercritical neutron star accretion columns in Cartesian geometry, including temperature-dependent, polarization-averaged Rosseland mean opacities accounting for…

Observations from the Rossi X-Ray Timing Explorer have shown the existence of high frequency quasi-periodic oscillations (HFQPOs) in the X-ray flux from accreting black hole binary systems. In at least two systems, these HFQPOs come in…

The observed quasi-periodic oscillations (QPOs) in low-mass X-ray binaries have been suggested to be probably related to the characteristic oscillation modes in the inner part of a relativistic accretion disk. In this paper we study the…

Binary systems with a neutron-star primary accreting from a companion star display variability in the X-ray band on time scales ranging from years to milliseconds. With frequencies of up to ~1300 Hz, the kilohertz quasi-periodic…

Accretion flows having low angular momentum and low viscosity can have standing shock waves. These shocks arise due to the presence of multiple sonic points in the flow. We study the region of the parameter space in which multiple sonic…

We continue our earlier studies of quasi-periodic oscillations (QPOs) in the power spectra of accreting, rapidly-rotating black holes that originate from the geometric "light echoes" of X-ray flares occurring within the black hole…

In the propagating oscillatory shock model, the oscillation of the post-shock region, i.e., the Compton cloud, causes the observed low-frequency quasi-periodic oscillations (QPOs). The evolution of QPO frequency is explained by the…

We consider the inner regions of accretion disks surrounding black holes and neutron stars and investigate the nonlinear time dependent evolution of thermal-viscous instabilities. The viscous stress is assumed to be proportional to the gas…

We report the development of a new tool to determine the origin of quasi-periodic oscillations (QPOs) in accretion disk systems. The technique uses the source energy spectrum and the energy dependence of the QPO fractional amplitude to…

Context. Theoretical arguments and numerical simulations of radiative shocks produced by the impact of the accreting gas onto young stars predict quasi-periodic oscillations in the emitted radiation. However, observational data do not show…

In this paper, we investigate for the first time the quasi-periodic oscillations (QPOs) that arise as a result of halting the Bondi-Hoyle-Lyttleton (BHL) accretion mechanism around a Kerr black hole. Unlike previous studies, which focused…

We have carried out a systematic study of the properties of the kilo-Hertz quasi-periodic oscillations (QPO) observed in the X-ray emission of the neutron star low-mass X-ray binary 4U1608-52, using archival data obtained with the Rossi…

One of the most dramatic discoveries made with the Rossi X-Ray Timing Explorer is that many accreting neutron stars in low-mass binary systems produce strong, remarkably coherent, high-frequency X-ray brightness oscillations. The 325-1200…

We present a theoretical model for the alternating phase lags associated with QPO fundamental and harmonic frequencies observed in some Galactic black-hole candidates. We assume that the accretion flow exhibits a transition from an outer…

We investigate the dynamics of transonic advective accretion flows around spinning black holes in the presence of viscosity. The spacetime of a Kerr black hole is approximated using a pseudo-potential. We study viscously driven shock…