相关论文: Inclination dependence of QPO phase lags in black …

Quasi-Periodic Oscillations (QPOs) are very puzzling since they remain totally unexplained by popular earlier models of accretion disks. The significant rms value in power density spectrum implies that the oscillation involves in the…

We perform the first systematic search of all NICER archival observations of black hole (and candidate) low-mass X-ray binaries for signatures of reverberation. Reverberation lags result from the light travel time difference between the…

X-ray low frequency quasi-periodic oscillations (LFQPOs) of black hole X-ray binaries, especially those type-C LFQPOs, are representative timing signals of black hole low/hard state and intermediate state, which has been suspected as to…

The physical origin of high-frequency QPOs (HFQPOs) in black-hole X-ray binaries remains an enigma despite many years of detailed observational studies. Although there exists a number of models for HFQPOs, many of these are simply "notions"…

We have investigated properties of the Quasi Periodic Oscillation (QPO) features in the accretion powered X-ray pulsar Cen X-3 over a period of about four years using observations carried out with the Proportional Counter Array (PCA) of the…

We model energy dependencies of the quasi periodic oscillations (QPO) in the model of disc epicyclic motions, with X-ray modulation caused by varying relativistic effects. The model was proposed to explain the high frequency QPO observed in…

Most black hole candidate X-ray binaries show Fourier time lags between softer and harder X-rays. The hard photons seem to arrive up to a few ms after the soft for a given Fourier frequency of the perturbation. The energy dependence of the…

The black hole X-ray binary GX\,339-4 showed an X-ray outburst during 2021. The {\it AstroSat} captured this outburst when the source entered into the intermediate flux state while the count rate was declining. The source showed an…

Quasi-periodic oscillations (QPOs) have been widely observed in black hole X-ray binaries (BHBs), which often exhibit significant X-ray variations. Extensive research has explored the long-term evolution of the properties of QPOs in BHBs.…

We present a new spectral-timing technique for phase-resolved spectroscopy and apply it to the low-frequency Type B quasi-periodic oscillation (QPO) from the black hole X-ray binary GX 339-4. We show that on the QPO time-scale the spectrum…

We investigate the accretion disk geometry in Galactic black hole sources by measuring the time delay between soft and hard X-ray emissions. Similar to the recent discoveries of anti-correlated hard X-ray time lags in Cyg X-3 and GRS…

We present a detailed analysis of the evolution of type-C quasiperiodic oscillations (QPOs) observed during the flaring state of the recently discovered black hole X-ray binary Swift J1727.8-1613, utilizing data from the Insight Hard X-ray…

Although low-frequency quasiperiodic oscillations (LFQPOs) are commonly detected in the X-ray light curves of accreting black hole X-ray binaries, their origin still remains elusive. In this study, we conduct phase-resolved spectroscopy in…

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…

Accreting stellar-mass black holes appear to populate two branches in a radio:X-ray luminosity plane. We have investigated the X-ray variability properties of a large number of black hole low-mass X-ray binaries, with the aim of unveiling…

We develop a simple physical model to describe the most common type of low-frequency quasi-periodic oscillations (QPOs) seen in a number of accreting black hole systems, as well as the shape of the relativistically broadened iron emission…

The X-ray variations of hard state black hole X-ray binaries above 2 keV show 'hard lags', in that the variations at harder energies follow variations at softer energies, with a time-lag \tau depending on frequency \nu approximately as \tau…

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…

Context. Quasi-periodic oscillations (QPOs) are a common feature of the power spectrums of X-ray binaries. Currently it is not possible to unambiguously differentiate the large number of proposed models to explain these phenomena through…

We present the discovery of a low-frequency $\approx 5.7$ Hz quasi-periodic oscillation (QPO) feature in observations of the black hole X-ray binary MAXI J1535-571 in its soft-intermediate state, obtained in September-October 2017 by the…