scholarly journals Time lags of the type-B quasi-periodic oscillation in MAXI J1348−630

2020 ◽  
Vol 496 (4) ◽  
pp. 4366-4371 ◽  
Author(s):  
Tomaso M Belloni ◽  
Liang Zhang ◽  
Nikolaos D Kylafis ◽  
Pablo Reig ◽  
Diego Altamirano
Keyword(s):  
Periodic Oscillation ◽  
High Signal ◽  
Time Lags ◽  
Type B ◽  
Quasi Periodic Oscillation ◽  
Black Hole Binaries ◽  
Relativistic Jet ◽  
Noise Data ◽  
Phase Lags ◽  
First Time

ABSTRACT The fast variability observed in the X-ray emission from black hole binaries has a very complex phenomenology, but offers the possibility to investigate directly the properties of the inner accretion flow. In particular, type-B oscillations in the 2–8 Hz range, observed in the soft-intermediate state, have been associated with the emission from a relativistic jet. We present the results of the timing and spectral analysis of a set of observations of the bright transient MAXI J1348−630 made with the NICER (Neutron Star Interior Composition Explorer) telescope. The observations are in the brightest part of the outburst and all feature a strong type-B quasi-periodic oscillation (QPO) at ∼4.5 Hz. We compute the energy dependence of the fractional rms and the phase lags at the QPO frequency, obtaining high signal-to-noise data and sampling for the first time at energies below 2 keV. The fractional rms decreases from more than 10 per cent at 9 keV to 0.6 per cent at 1.5 keV, and is constant below that energy. Taking the 2–3 keV band as reference, photons at all energies show a hard lag, increasing with the distance from the reference band. The behaviour below 2 keV has never been observed before, due to the higher energy bandpass of previous timing instruments. The energy spectrum can be fitted with a standard model for this state, consisting of a thin disc component and a harder power law, plus an emission line between 6 and 7 keV. We discuss the results, concentrating on the phase lags, and show that they can be interpreted within a Comptonization model.

scholarly journals A variable-frequency HFQPO in GRS 1915+105 as observed with AstroSat

2019 ◽  
Vol 489 (1) ◽  
pp. 1037-1043 ◽  
Author(s):  
Tomaso M Belloni ◽  
Dipankar Bhattacharya ◽  
Pietro Caccese ◽  
Varun Bhalerao ◽  
Santosh Vadawale ◽  
...  
Keyword(s):  
Periodic Oscillation ◽  
Large Area ◽  
Quasi Periodic Oscillation ◽  
X Ray ◽  
Phase Lags ◽  
Time Variations ◽  
Area X ◽  
First Time ◽  
Observation Period

ABSTRACT From the analysis of more than 92 ks of data obtained with the Large Area X-Ray Proportional Counter (LAXPC) instrument onboard AstroSat we have detected a clear high-frequency quasi-periodic oscillation (HFQPO) whose frequency varies between 67.4 and 72.3 Hz. In the classification of variability classes of GRS 1915+105, at the start of the observation period the source was in class ω and at the end the variability was that of class μ: both classes are characterized by the absence of hard intervals and correspond to disc-dominated spectra. After normalization to take into account time variations of the spectral properties as measured by X-ray hardness, the QPO centroid frequency is observed to vary along the hardness–intensity diagram, increasing with hardness. We also measure phase lags that indicate that HFQPO variability at high energies lags that at lower energies and detect systematic variations with the position on the hardness–intensity diagram. This is the first time that (small) variations of the HFQPO frequency and lags are observed to correlate with other properties of the source. We discuss the results in the framework of existing models, although the small (7 per cent) variability observed is too small to draw firm conclusions.

scholarly journals A systematic analysis of the phase lags associated with the type-C quasi-periodic oscillation in GRS 1915+105

2020 ◽  
Vol 494 (1) ◽  
pp. 1375-1386 ◽  
Author(s):  
Liang Zhang ◽  
Mariano Méndez ◽  
Diego Altamirano ◽  
Jinlu Qu ◽  
Li Chen ◽  
...  
Keyword(s):  
Second Harmonic ◽  
Periodic Oscillation ◽  
Energy Spectra ◽  
Phase Lag ◽  
Physical Origin ◽  
Systematic Analysis ◽  
Quasi Periodic Oscillation ◽  
Phase Lags ◽  
Type C ◽  
Subharmonic Frequency

ABSTRACT We present a systematic analysis of the phase lags associated with the type-C quasi-periodic oscillations (QPOs) in GRS 1915+105 using RXTE data. Our sample comprises 620 RXTE observations with type-C QPOs ranging from ∼0.4 to ∼6.3 Hz. Based on our analysis, we confirm that the QPO phase lags decrease with QPO frequency, and change sign from positive to negative at a QPO frequency of ∼2 Hz. In addition, we find that the slope of this relation is significantly different between QPOs below and above 2 Hz. The relation between the QPO lags and QPO rms can be well fitted with a broken line: as the QPO lags go from negative to positive, the QPO rms first increases, reaching its maximum at around zero lag, and then decreases. The phase-lag behaviour of the subharmonic of the QPO is similar to that of the QPO fundamental, where the subharmonic lags decrease with subharmonic frequency and change sign from positive to negative at a subharmonic frequency of ∼1 Hz; on the contrary, the second harmonic of the QPO shows a quite different phase-lag behaviour, where all the second harmonics show hard lags that remain more or less constant. For both the QPO and its (sub)harmonics, the slope of the lag–energy spectra shows a similar evolution with frequency as the average phase lags. This suggests that the lag–energy spectra drive the average phase lags. We discuss the possibility for the change in lag sign, and the physical origin of the QPO lags.

scholarly journals A global study of type B quasi-periodic oscillation in black hole X-ray binaries

2016 ◽  
Vol 466 (1) ◽  
pp. 564-573 ◽  
Author(s):  
H. Q. Gao ◽  
Liang Zhang ◽  
Yupeng Chen ◽  
Zhen Zhang ◽  
Li Chen ◽  
...  
Keyword(s):  
Black Hole ◽  
Periodic Oscillation ◽  
Type B ◽  
Quasi Periodic Oscillation ◽  
X Ray ◽  
Global Study ◽  
X Ray Binaries

scholarly journals Angular velocity perturbations inducing the Papaloizou–Pringle instability and QPOs in the torus around the black hole

2017 ◽  
Vol 32 (20) ◽  
pp. 1750108 ◽  
Author(s):  
Orhan Donmez
Keyword(s):  
Black Hole ◽  
Angular Velocity ◽  
Dynamic Response ◽  
Numerical Simulations ◽  
Numerical Study ◽  
Periodic Oscillation ◽  
Quasi Periodic Oscillation ◽  
Rotating Black Hole ◽  
Extensive Analysis ◽  
First Time

In this paper, a numerical study of the dynamic of the non-self-gravitating, unmagnetized, non-axisymmetric, and rotating the torus around the non-rotating black hole is presented. We investigate the instability of the rotating torus subject to perturbations presented by increasing or decreasing the angular velocity of the stable torus. We have done, for the first time, an extensive analysis of the torus dynamic response to the perturbation of the angular velocity of the stable torus. We show how the high, moderate, and low values of the perturbations affect the torus dynamic and help us to understand the properties of the instability and quasi-periodic oscillation (QPO). Our numerical simulations indicate the presence of Papaloizou–Pringle instability (PPI) with global m = 1 mode and QPOs for the moderate and lower values of the perturbations on the angular velocity of the stable torus. Furthermore, with the lower values of the perturbations, the torus can lead to a wiggling initially and then PPI is produced in it. Finally, the matter of the torus would be dissipated due to the presence of a strong torque.

scholarly journals The Evolution of the Phase Lags Associated with the Type-C Quasi-periodic Oscillation in GX 339–4 during the 2006/2007 Outburst

2017 ◽  
Vol 845 (2) ◽  
pp. 143 ◽  
Author(s):  
Liang Zhang ◽  
Yanan Wang ◽  
Mariano Méndez ◽  
Li Chen ◽  
Jinlu Qu ◽  
...  
Keyword(s):  
Periodic Oscillation ◽  
Quasi Periodic Oscillation ◽  
Phase Lags ◽  
Type C

scholarly journals Time-domain variability properties of XTE J1650−500 during its 2001 outburst: evidence of disc–jet connection

2020 ◽  
Vol 497 (4) ◽  
pp. 4222-4230
Author(s):  
Arka Chatterjee ◽  
Broja G Dutta ◽  
Prantik Nandi ◽  
Sandip K Chakrabarti
Keyword(s):  
Black Hole ◽  
Time Lag ◽  
Periodic Oscillation ◽  
Time Lags ◽  
Central Black Hole ◽  
Quasi Periodic Oscillation ◽  
X Ray ◽  
Transient Sources ◽  
Unique Nature ◽  
Hard State

ABSTRACT The evolution of variability properties of Galactic transient sources is a diagnostic tool to understand various regimes of the accretion flow and its dynamics close to the central black hole. In this paper, we concentrate on the variability properties of the X-ray transient XTE J1650−500 and investigate the evolution of viscous delay, time lag, quasi-periodic oscillation (QPO) frequency, and their energy dependence throughout the rising phase as observed by Rossi X-ray Timing Explorer(RXTE) during its outburst in 2001. Our analysis reveals (1) a delay of 12 ± 1 d between 1 d-averaged hard (5–12 keV) and soft (1.5–3 keV) photon light curves as observed by RXTE/ASM; (2) QPOs with high rms values are observed in lower energy (4–8 keV) range; (3) the QPO frequencies and associated time lags were anticorrelated during the initial days of the rising phase, and later on, they were found to be correlated; (4) the time lags of Fe-line photons with respect to hard and soft photons remained almost constant during the initial days of hard state and the lag magnitude increased during the state transition. We perform comparative studies with outbursts of GX 339−4 and XTE J1550−564. We find the evolution of time lags associated with the QPO characteristics during the outburst – stronger QPOs at low energy and constant lags of broad Fe-line photons present a unique nature of outburst profile in XTE J1650−500. The possible cause of such variabilities is explained by considering disc–jet geometry closer to the central black hole.

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