相关论文: Study of timing evolution from non-variable to str…

We report the results of the analysis of an AstroSat observation of the Black Hole candidate MAXI J1535-571 during its Hard Intermediate state. We studied the evolution of the spectral and timing parameters of the source during the…

GRS 1915+105 can show type-C quasi-periodic oscillations (QPOs) in the power density spectrum. A high-frequency QPO (HFQPO) at 67 Hz has been observed in this source, albeit less often than the type-C QPOs. Besides these features, GRS…

Highly variable Black Hole X-ray Binary (BHXB) GRS~1915+105 has shown many flaring classes when the source oscillates between the High Soft state (HS) and the Hard Intermediate state (HIMS) with a transition time of less than 10 s. The…

We report a timing analysis of the black hole binary GRS 1915+105 with the NuSTAR observatory. A strong type-C QPO below 2 Hz appears in the power density spectrum during the whole observation, whose frequency is correlated with the 3-25…

We report the first detection of evolving Low-Frequency Quasi-periodic Oscillation (LFQPO) frequencies in hard X-rays upto $100$ keV with $AstroSat/LAXPC$ during `unusual' outburst phase of Swift J1727.8-1613 in hard-intermediate state…

Powerful relativistic jets are one of the ubiquitous features of accreting black holes in all scales. GRS 1915+105 is a well-known fast-spinning black-hole X-ray binary with a relativistic jet, termed as a ``microquasar'', as indicated by…

The microquasar GRS1915+105 was observed by BeppoSAX in October 2000 for about ten days while the source was in \rho-mode, which is characterized by a quasi-regular type I bursting activity. This paper presents a systematic analysis of the…

The study of fast variability properties in X-ray binaries advances our understanding of the physical processes and geometric properties of the accretion flow around the compact object. In this work, we study the evolution of the timing…

In this work, we explore the long-term variability properties of the blazar PKS 0219-164 in the radio and the $\gamma$-ray regime, utilizing the OVRO 15 GHz and the \fermi/LAT observations from the period 2008--2017. We found that…

While the dynamical origin of the variability observed in Galactic Black hole systems, such as quasi-periodic oscillations (QPOs), are still a matter of debate, insight into the radiative components responsible for such behaviour can be…

We investigate the complex behavior of energy- and frequency-dependent time/phase lags in the plateau state and the radio-quiet hard state of GRS 1915+105. In our timing analysis, we find that when the source is faint in the radio, QPOs are…

We present a timing analysis of the black hole X-ray binary (BHXRB) 4U 1630-47 using AstroSat observations from 10-19 March 2023, for the first time capturing a rare and rapid transition in variability properties. Within less than a day,…

Simultaneous X-ray (BeppoSAX, 0.1-300 keV) and radio (Ryle Telescope, 15 GHz) observations of the superluminal galactic source GRS 1915+105 in high flux state were carried out starting October 1996. Here we present the simultaneous…

Using observations with the Rossi X-ray Timing Explorer, we examine the behavior of 2-10 Hz quasi-periodic oscillations (QPOs) during spectrally-hard dips in the x-ray light curve of GRS 1915+105 that are accompanied by infrared flares. Of…

We investigate the origin of the ubiquitous 0.5 - 10 Hz QPO in the Galactic microquasar GRS 1915+105. Using the archival X-ray data from RXTE, we make a wide band X-ray spectral fitting to the source during a low-hard state observed in 1999…

We present here results from the X-ray timing and spectral analysis of the X-ray binary Cyg X-3 using observations from Large Area X-ray Proportional Counter (LAXPC) on-board AstroSat. Consecutive lightcurves observed over a period of one…

IGR J17091--3624 is a transient galactic black hole which has a distinct quasi-periodic variability known as `heartbeat', similar to the one observed in GRS 1915+105. In this paper, we report the results of $\sim 125$ ks \textit{AstroSat}…

We present the detection of type C quasi-periodic oscillation (QPO) along with upper harmonic at respective frequencies of $\sim0.6$ Hz and $\sim1.2$ Hz in the single AstroSat observation taken during the 2016 outburst of the low-mass black…

Most models of the low frequency quasi periodic oscillations (QPOs) in low-mass X-ray binaries (LMXBs) explain the dynamical properties of those QPOs. On the other hand, in recent years reverberation models that assume a lamp-post geometry…

We report the discovery in archival Rossi X-ray Timing Explorer (RXTE) data of a 40 Hz quasiperiodic oscillation (QPO) in the hard X-ray flux from the galactic microquasar GRS 1915+105. The QPO is detected only in the hard X-ray band above…