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From the analysis of more than 92 ks of data obtained with the laxpc instrument on board Astrosat we have detected a clear high-frequency QPO whose frequency varies between 67.4 and 72.3 Hz. In the classification of variability classes of…

High Energy Astrophysical Phenomena · Physics 2019-08-14 Tomaso M. Belloni , Dipankar Bhattacharya , Pietro Caccese , Varun Bhalerao , Santosh Vadawale , J. S. Yadav

We present a comprehensive temporal and spectral analysis of the 'softer' variability classes ($i.e.$, $\theta$, $\beta$, $\delta$, $\rho$, $\kappa$, $\omega$ and $\gamma$) of the source GRS 1915+105 observed by AstroSat during $2016-2021$…

High Energy Astrophysical Phenomena · Physics 2022-04-06 Seshadri Majumder , H. Sreehari , Nafisa Aftab , Tilak Katoch , Santabrata Das , Anuj Nandi

We report the results of AstroSat observations of GRS 1915$+$105 obtained using 100 ks guaranteed-time (GT) during the soft state. The Color-Color Diagram (CCD) indicates a variability class of $\delta$ with the detection of High Frequency…

High Energy Astrophysical Phenomena · Physics 2020-11-18 Sreehari H. , Anuj Nandi , Santabrata Das , V. K. Agrawal , Samir Mandal , M. C. Ramadevi , Tilak Katoch

We present a comprehensive study of GRS 1915+105 in wide energy band ($0.5-60$ keV) using AstroSat observations during the period of $2016-2019$. The MAXI X-ray lightcurve of the source shows rise and decay profiles similar to canonical…

High Energy Astrophysical Phenomena · Physics 2022-03-30 Athulya M. P. , Radhika D. , V. K. Agrawal , Ravishankar B. T. , Sachindra Naik , Samir Mandal , Anuj Nandi

GRS 1915+105 is observed in an 'obscured' phase since May 2019, exhibiting steady and low X-ray luminosities, while being intervened by sporadic re-brightenings. In this work, we perform a comprehensive and wide-band analysis of the…

High Energy Astrophysical Phenomena · Physics 2023-07-11 Athulya M. P. , Anuj Nandi

We explore the timing and spectral properties of GRS 1915+105 based on X-ray observations of NICER and Insight-HXMT during the long outburst from 2017 to 2021. We find a new class of variability in the rising stage of the outburst that…

High Energy Astrophysical Phenomena · Physics 2025-09-19 Zhihong Shi , Qingwen Wu , Zhen Yan , Bing Lyu , Hao Liu

The X-ray emission from the microquasar GRS 1515+105 shows, together with a very complex variability on different time scales, the presence of low-frequency quasi periodic oscillations (LFQPO) at frequencies lower than 30 Hz. In this paper,…

High Energy Astrophysical Phenomena · Physics 2020-09-17 E. Massaro , F. Capitanio , M. Feroci , T. Mineo

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…

High Energy Astrophysical Phenomena · Physics 2022-04-27 Yuexin Zhang , Mariano Méndez , Federico García , Konstantinos Karpouzas , Liang Zhang , Honghui Liu , Tomaso M. Belloni , Diego Altamirano

We report the results of a systematic timing analysis of RXTE observations of GRS 1915+105 when the source was in its variability class theta, characterized by alternating soft and hard states on a time scale of a few hundred seconds. The…

Astrophysics · Physics 2009-11-11 T. Belloni , P. Soleri , P. Casella , M. Mendez , S. Migliari

We present a comprehensive analysis of the 'canonical' soft state ($\gamma$, $\delta$, and $\phi$ spectral variability classes) of the black hole binary GRS 1915+105, using RXTE, AstroSat, and NuSTAR data from 1996 to 2017 to investigate…

High Energy Astrophysical Phenomena · Physics 2025-04-22 Prajjwal Majumder , Broja G. Dutta , Anuj Nandi

We present, for the first time, an in-depth dynamical analysis of the spectro-temporal properties of the soft variability classes ($\delta$, $\kappa$, $\omega$, and $\gamma$) of GRS 1915+105 during the detection of $\sim$70 Hz…

High Energy Astrophysical Phenomena · Physics 2025-06-03 Sreehari Harikesh , Seshadri Majumder , Santabrata Das , Anuj Nandi

The Galactic black hole GRS 1915+105 exhibits generic High-Frequency Quasi-periodic Oscillations (HFQPOs) at $\sim$ 67 Hz only during the radio-quiet 'softer' variability classes. We present the time-lag properties associated with HFQPOs in…

High Energy Astrophysical Phenomena · Physics 2023-11-09 Prajjwal Majumder , Broja G. Dutta , Anuj Nandi

From data obtained from the PCA in the 2-11 keV and 11-30.5 keV energy range, GRS 1915+105 is seen during RXTE observations between 1996 May and October on two separate branches in a hardness intensity diagram. On the hard branch, GRS…

Astrophysics · Physics 2009-10-28 Xingming Chen , Jean H. Swank , Ronald E. Taam

We present a comprehensive analysis of Low Frequency Quasi-periodic Oscillation (LFQPO) associated time-lags in the persistently variable black hole binary GRS 1915+105 using 441 ks of \textit{AstroSat} observations from March 2016 to March…

High Energy Astrophysical Phenomena · Physics 2026-03-18 Prajjwal Majumder , Broja G. Dutta , Anuj Nandi

We perform a comparative spectro-temporal analysis on the variability classes of GRS 1915+105 and IGR J17091-3624 to draw inferences regarding the underlying accretion flow mechanism. The $\nu$, as well as C2 class Rossi X-Ray Timing…

High Energy Astrophysical Phenomena · Physics 2022-03-14 Anuvab Banerjee , Ayan Bhattacharjee , Dipak Debnath , Sandip K. Chakrabarti

From the study of X-ray light curve and color-color diagram of the low mass X-ray binary GRS 1915+105, observed by on board proportional counter array (PCA) of Rossi X-ray Timing Explorer (RXTE), we discover a new class of variability,…

High Energy Astrophysical Phenomena · Physics 2009-06-26 Mayukh Pahari , Sabyasachi Pal

We present the first quick look analysis of data from nine {\it AstroSat}'s LAXPC observations of GRS 1915+105 during March 2016 when the source had the characteristics of being in Radio-quiet $\chi$ class. We find that a simple empirical…

GRS 1915+105 has been well studied since its discovery, and is well-known for its complex light curve variability. Using the full currently available Insight-HXMT dataset from July 2017 to June 2023, we make a comprehensive spectral-timing…

High Energy Astrophysical Phenomena · Physics 2025-10-14 Xiao Chen , Weiping Liu , Wei Wang

We report on the timing analysis of RXTE observations of the Galactic micro-quasar GRS 1915+105 performed in 2003. Out of a total of six times ~20 ks, we focus here only on the three observations during which GRS 1915+105 is found in a…

Astrophysics · Physics 2009-11-10 J. Rodriguez , S. Corbel , D. C. Hannikainen , T. Belloni , A. Paizis , O. Vilhu

We present a detailed X-ray study of the microquasar GRS 1915+105 during a variability class transition observed in 2000 June with the PPCs of the Indian X-ray Astronomy Experiment. We supplement this observation with data from the RXTE…

Astrophysics · Physics 2009-11-07 S. Naik , P. C. Agrawal , A. R. Rao , B. Paul
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