相关论文: Global MHD instabilities: from Low Frequency to Hi…

We present a possible explanation for the high-frequency Quasi-Periodic Oscillations of microquasars by an MHD instability that combines the physics developed, in different contexts, for the Accretion-Ejection Instability, the Rossby-Wave…

This is the first of two papers in which we address the physics of the low-frequency Quasi-Periodic Oscillation (QPO) of X-ray binaries, in particular those hosting a black hole. We discuss and repeat the recent analysis and spectral…

High resolution observations of Sgr A* have revealed a wide variety of phenomena, ranging from intense rapid flares to quasi-periodic oscillations, making this object an ideal system to study the properties of low luminosity accreting black…

We propose a unified model to explain Quasi-Periodic-Oscillation (QPO), particularly of high frequency, observed from black hole and neutron star systems globally. We consider accreting systems to be damped harmonic oscillators exhibiting…

The Accretion-Ejection Instability has been proposed to explain the low frequency Quasi-Periodic Oscillation (QPO) observed in low-mass X-Ray Binaries, in particular Black-Hole candidates. Its frequency, typically a fraction of the…

We report transient quasi-periodic oscillations (QPOs) on minute timescales in relativistic, radiative models of the galactic center source Sgr A*. The QPOs result from nonaxisymmetric $m=1$ structure in the accretion flow excited by MHD…

In recent years, near-IR and X-ray flares have been detected from the Galaxy's central radio point source, Sagittarius A* (Sgr A*), believed to be a \~3.10^6 solar masses supermassive black hole. In some cases, the transient emission…

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…

High-frequency quasi-periodic oscillations (QPOs) appear in general-relativistic magnetohydrodynamic simulations of magnetically choked accretion flows around rapidly rotating black holes (BHs). We perform polarized radiative transfer…

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 suggest a possible explanation for the high frequency quasi-periodic oscillations (QPOs) in black hole low mass X-ray binaries. By solving the perturbation general relativistic magnetohydrodynamic equations, we find two stable modes of…

We explore the influence of non-geodesic pressure forces that are present in an accretion disk on the frequencies of its axisymmetric and non-axisymmetric epicyclic oscillation modes. {We discuss its implications for models of…

The multi-resonance orbital model of high-frequency quasi-periodic oscillations (HF QPOs) enables precise determination of the black hole dimensionless spin a if observed set of oscillations demonstrates three (or more) commensurable…

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,…

The study of quasi-periodic oscillations (QPOs) of X-ray flux observed in the stellar-mass black hole binaries can provide a powerful tool for testing of the phenomena occurring in strong gravity regime. The high frequency (HF) QPOs usually…

We establish a unified model to explain Quasi-Periodic-Oscillation (QPO) observed from black hole and neutron star systems globally. This is based on the accreting systems thought to be damped harmonic oscillators with higher order…

In all four microquasars which show double peak kHz QPOs, the ratio of the two frequencies is 3:2. This strongly supports the suggestion that twin peak kHz QPOs are due to a resonance between some modes of accretion disk oscillations. Here,…

We suggest that persistent low-frequency quasi-periodic oscillations (QPOs) detected in X-ray, ultraviolet, optical energy ranges the black hole (BH) sources XTE J1118+480, GRO J1655-40 LMC X-1 at ~ 0.1 Hz, and QPOs in HZ Her/Her X-1 at ~…

We present an analysis of the high frequency timing properties of the April-May 2000 outburst of the black hole candidate and Galactic microquasar XTE J1550-564, measured with the Rossi X-ray Timing Explorer. The rapid X-ray variability we…

For all available pseudo-Schwarzschild potentials, we provide a non-self-similar model of coupled accretion-outflow system in connection to the Quasi Periodic Oscillation (QPO) of the black hole powered galactic microquasars and the…