scholarly journals The energy dependence of the three types of low-frequency quasi-periodic oscillations in the black hole candidate H1743−322

2013 ◽  
Vol 433 (1) ◽  
pp. 412-420 ◽  
Author(s):  
Z. B. Li ◽  
S. Zhang ◽  
J. L. Qu ◽  
H. Q. Gao ◽  
H. H. Zhao ◽  
...  
Galaxies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 25
Author(s):  
Debjit Chatterjee ◽  
Arghajit Jana ◽  
Kaushik Chatterjee ◽  
Riya Bhowmick ◽  
Sujoy Kumar Nath ◽  
...  

We study the properties of the faint X-ray activity of Galactic transient black hole candidate XTE J1908+094 during its 2019 outburst. Here, we report the results of detailed spectral and temporal analysis during this outburst using observations from Nuclear Spectroscopic Telescope Array (NuSTAR). We have not observed any quasi-periodic-oscillations (QPOs) in the power density spectrum (PDS). The spectral study suggests that the source remained in the softer (more precisely, in the soft–intermediate) spectral state during this short period of X-ray activity. We notice a faint but broad Fe Kα emission line at around 6.5 keV. We also estimate the probable mass of the black hole to be 6.5−0.7+0.5M⊙, with 90% confidence.


2020 ◽  
Vol 493 (2) ◽  
pp. 2452-2462 ◽  
Author(s):  
Kaushik Chatterjee ◽  
Dipak Debnath ◽  
Debjit Chatterjee ◽  
Arghajit Jana ◽  
Sandip K Chakrabarti

ABSTRACT Spectral and timing properties of the stellar-mass black hole candidate XTE J1752-223 during its 2009-10 outburst are studied using RXTE PCA data in the 2.5–25 keV energy range. Low frequency quasi-periodic oscillations are seen during outburst. The spectral analysis is done using two types of models: one is the combined disc blackbody plus power-law model and the other is Transonic flow solution based Two Component Advective Flow (TCAF) model. Light-curve profiles and evolution of hardness ratios are studied using MAXI GSC and Swift BAT data. Based on the evolution of the temporal and the spectral properties, we find that the object evolved through the following spectral states: hard, hard-intermediate, and soft-intermediate/soft. From the TCAF model fitted spectral analysis, we also estimate the probable mass of the black hole in the range of 8.1−11.9 M⊙, and more precisely, the mass appears to be 10 ± 1.9 M⊙.


2015 ◽  
Vol 448 (2) ◽  
pp. 1298-1304 ◽  
Author(s):  
Devraj D. Pawar ◽  
Sara Motta ◽  
K. Shanthi ◽  
Dipankar Bhattacharya ◽  
Tomaso Belloni

2005 ◽  
Vol 623 (1) ◽  
pp. 383-391 ◽  
Author(s):  
Jeroen Homan ◽  
Jon M. Miller ◽  
Rudy Wijnands ◽  
Michiel van der Klis ◽  
Tomaso Belloni ◽  
...  

2019 ◽  
Vol 488 (1) ◽  
pp. 720-727 ◽  
Author(s):  
Yash Bhargava ◽  
Tomaso Belloni ◽  
Dipankar Bhattacharya ◽  
Ranjeev Misra

Abstract 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 observation. The observation covered a period of ∼5 d and consisted of 66 continuous segments, corresponding to individual spacecraft orbits. Each segment was analysed independently. The source count rate increased roughly linearly by ∼30 per cent. We modelled the spectra as a combination of radiation from a thermal disc component and a power law. The timing analysis revealed the presence of strong quasi-periodic oscillations with centroid frequency νQPO fluctuating in the range of 1.7–3.0 Hz. We found a tight correlation between the QPO centroid frequency νQPO and the power-law spectral index Γ, while νQPO appeared not to be correlated with the linearly increasing flux itself. We discuss the implications of these results on physical models of accretion.


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