scholarly journals An imperfect double: probing the physical origin of the low-frequency quasi-periodic oscillation and its harmonic in black hole binaries

2013 ◽  
Vol 438 (1) ◽  
pp. 657-662 ◽  
Author(s):  
Magnus Axelsson ◽  
Chris Done ◽  
Linnea Hjalmarsdotter
Keyword(s):  
Black Hole ◽  
Low Frequency ◽  
Periodic Oscillation ◽  
Physical Origin ◽  
Quasi Periodic Oscillation ◽  
Black Hole Binaries

scholarly journals MAXI J1820+070 with NuSTAR I. An increase in variability frequency but a stable reflection spectrum: coronal properties and implications for the inner disc in black hole binaries

2019 ◽  
Vol 490 (1) ◽  
pp. 1350-1362 ◽  
Author(s):  
D J K Buisson ◽  
A C Fabian ◽  
D Barret ◽  
F Fürst ◽  
P Gandhi ◽  
...  
Keyword(s):  
Black Hole ◽  
Low Frequency ◽  
Periodic Oscillation ◽  
Thermal Electron ◽  
X Ray ◽  
Black Hole Binaries ◽  
Black Hole Candidate ◽  
Long Duration ◽  
Hard State ◽  
Characteristic Features

ABSTRACT MAXI J1820+070 (optical counterpart ASASSN-18ey) is a black hole candidate discovered through its recent very bright outburst. The low extinction column and long duration at high flux allow detailed measurements of the accretion process to be made. In this work, we compare the evolution of X-ray spectral and timing properties through the initial hard state of the outburst. We show that the inner accretion disc, as measured by relativistic reflection, remains steady throughout this period of the outburst. Nevertheless, subtle spectral variability is observed, which is well explained by a change in coronal geometry. However, characteristic features of the temporal variability – low-frequency roll-over and quasi-periodic oscillation frequency – increase drastically in frequency, as the outburst proceeds. This suggests that the variability time-scales are governed by coronal conditions rather than solely by the inner disc radius. We also find a strong correlation between X-ray luminosity and coronal temperature. This can be explained by electron pair production with a changing effective radius and a non-thermal electron fraction of $\sim 20$ per cent.

scholarly journals A NICER Discovery of a Low-frequency Quasi-periodic Oscillation in the Soft-intermediate State of MAXI J1535–571

2018 ◽  
Vol 865 (2) ◽  
pp. L15 ◽  
Author(s):  
A. L. Stevens ◽  
P. Uttley ◽  
D. Altamirano ◽  
Z. Arzoumanian ◽  
P. Bult ◽  
...  
Keyword(s):  
Intermediate State ◽  
Low Frequency ◽  
Periodic Oscillation ◽  
Quasi Periodic Oscillation

scholarly journals Constraints on ultra-low-frequency gravitational waves with statistics of pulsar spin-down rates

2019 ◽  
Vol 489 (3) ◽  
pp. 3547-3552
Author(s):  
Hiroki Kumamoto ◽  
Yuya Imasato ◽  
Naoyuki Yonemaru ◽  
Sachiko Kuroyanagi ◽  
Keitaro Takahashi
Keyword(s):  
Black Hole ◽  
Gravitational Waves ◽  
Time Derivative ◽  
Low Frequency ◽  
Upper Bounds ◽  
Galactic Centre ◽  
Frequency Range ◽  
Rate Distribution ◽  
Black Hole Binaries ◽  
Supermassive Black Hole

Abstract We probe ultra-low-frequency gravitational waves (GWs) with statistics of spin-down rates of millisecond pulsars (thereafter MSPs) by a method proposed in our previous work. The considered frequency range is 10−12 Hz ≲ fGW ≲ 10−10  Hz . The effect of such low-frequency GWs appears as a bias to spin-down rates that has a quadrupole pattern in the sky. We use the skewness of the spin-down rate distribution and the number of MSPs with negative spin-down rates to search for the bias induced by GWs. Applying this method to 149 MSPs selected from the ATNF pulsar catalogue, we derive upper bounds on the time derivative of the GW amplitudes of $\dot{h} \lt 6.2 \times 10^{-18}~{\rm s}^{-1}$ and $\dot{h} \lt 8.1 \times 10^{-18}~{\rm s}^{-1}$ in the directions of the Galactic Centre and M87, respectively. Approximating the GW amplitude as $\dot{h} \sim 2 \pi f_{\rm GW} h$, the bounds translate into h < 3 × 10−8 and h < 4 × 10−8, respectively, for fGW = 1/(1000 yr). Finally, we give the implications to possible supermassive black hole binaries at these sites.

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.

On the origin of the low-frequency QPO in GRS 1915+105 ρ state

2012 ◽  
Vol 8 (S291) ◽  
pp. 565-567
Author(s):  
Shu-Ping Yan ◽  
Na Wang ◽  
Guo-Qiang Ding
Keyword(s):  
Spectral Study ◽  
Timing Analysis ◽  
Low Frequency ◽  
Periodic Oscillation ◽  
Quasi Periodic Oscillation ◽  
Contrast Analysis

AbstractWe performed a phase-resolved timing analysis of GRS 1915+105 in its ρ state and identify detailed ρ cycle evolution of frequency, amplitude and coherence of the low-frequency quasi-periodic oscillation (LFQPO). We combined our timing results with the spectral study by Neilsen et al. (2011) to do an elaborate contrast analysis. The results are naturally explained by tying the LFQPO to the corona.

Sign in / Sign up

Export Citation Format

Share Document