scholarly journals Re-observing the NLS1 galaxy RE J1034+396 – II. New insights on the soft X-ray excess, QPO, and the analogy with GRS 1915+105

2020 ◽  
Vol 500 (2) ◽  
pp. 2475-2495
Author(s):  
Chichuan Jin ◽  
Chris Done ◽  
Martin Ward
Keyword(s):  
Active Galactic Nucleus ◽  
Vertical Structure ◽  
Accretion Rate ◽  
Timing Analysis ◽  
Periodic Oscillation ◽  
Phase Lag ◽  
Quasi Periodic Oscillation ◽  
X Ray ◽  
Hot Corona ◽  
Physical Analogy

ABSTRACT The active galactic nucleus (AGN) RE J1034+396 displays the most significant X-ray quasi-periodic oscillation (QPO) detected so far. We perform a detailed spectral-timing analysis of our recent simultaneous XMM–Newton, NuSTAR, and Swift observations. We present the energy dependence of the QPO’s frequency, rms, coherence, and phase lag, and model them together with the time-averaged spectra. Our study shows that four components are required to fit all the spectra. These components include an inner disc component (diskbb), two warm corona components (CompTT-1 and CompTT-2), and a hot corona component (nthComp). We find that diskbb, CompTT-2 (the hotter but less luminous component), and nthComp all contain the QPO signal, while CompTT-1 only exhibits stochastic variability. By fitting the lag spectrum, we find that the QPO in diskbb leads CompTT-2 by 679 s, and CompTT-2 leads nthComp by 180 s. By only varying the normalizations, these components can also produce good fits to the time-averaged and variability spectra obtained from previous observations when QPOs were present and absent. Our multiwavelength study shows that the detectability of the QPO does not depend on the contemporaneous mass accretion rate. We do not detect a significant Iron K α emission line, or any significant reflection hump. Finally, we show that the rms and lag spectra in the latest observation are very similar to the 67-Hz QPO observed in the micro-quasar GRS 1915+105. These new results support the physical analogy between these two sources. We speculate that the QPO in both sources is due to the expansion/contraction of the vertical structure in the inner disc.

The parallel tracks of kHz QPOs in low-mass X-ray binary 4U 1728−34: explorer of the bimodal accretion modes

2020 ◽  
Vol 497 (3) ◽  
pp. 2893-2898
Author(s):  
De-Hua Wang ◽  
Cheng-Min Zhang
Keyword(s):  
Neutron Star ◽  
Accretion Rate ◽  
Periodic Oscillation ◽  
Quasi Periodic Oscillation ◽  
X Ray ◽  
Parallel Track ◽  
Theoretical Assumptions ◽  
Low Mass

ABSTRACT Parallel tracks in the relation between the lower kilohertz quasi-periodic oscillation (kHz QPO) frequency ν1 and the X-ray intensity I have been observed in the neutron star low-mass X-ray binary (NS-LMXB) 4U 1728−34, and we try to ascribe these phenomena to the bimodal accretion modes, i.e. the disc accretion and radial accretion. For the source with one constant radial accretion rate $\dot{M}_{\rm r}$, as the increase of the disc accretion rate $\dot{M}_{\rm d}$, the NS magnetosphere-disc radius can shrink from ∼18 to ∼16 km, while ν1 increases from ∼670 to ∼870 Hz. Then, due to the increase of the kHz QPO frequency and total X-ray intensity Itot, the source will trace out an oblique track in ν1–I relation. While, if the source enters another constant radial accretion rate due to the variation of the accretion environment, the increase of the disc accretion rate can arise another parallel track in ν1–I relation. Finally, the reliability of the theoretical assumptions, the variability of the accretion radius and accretion rate, as well as the dependence of the two accretion modes, are also investigated and discussed.

ON THE HBO MECHANISM OF X-RAY NEUTRON STAR

2001 ◽  
Vol 10 (05) ◽  
pp. 625-632 ◽  
Author(s):  
C. M. ZHANG
Keyword(s):  
Neutron Star ◽  
Empirical Formula ◽  
Accretion Rate ◽  
Periodic Oscillation ◽  
Precession Frequency ◽  
Relativistic Motion ◽  
Quasi Periodic Oscillation ◽  
Motion Mechanism ◽  
X Ray ◽  
Proposed Model

We ascribe the 15–60 Hz Quasi Periodic Oscillation (QPO) to the periastron precession frequency of the orbiting accreted matter at the boundary of magnetosphere-disk of X-ray neutron star (NS). Considering the relativistic motion mechanism for the kHz QPO, that the radii of the inner disk and magnetosphere-disk of NS are correlated with each other by a factor is assumed. The obtained conclusions include: all QPO frequencies increase with increasing the accretion rate. The theoretical relations between 15–60 Hz QPO (HBO) frequency and the twin kHz QPOs are similar to the measured empirical formula. Further, the better fitted NS mass by the proposed model is about 1.9 solar masses for the detected LMXBs.

scholarly journals Reobserving the NLS1 galaxy RE J1034+396 – I. The long-term, recurrent X-ray QPO with a high significance

2020 ◽  
Vol 495 (4) ◽  
pp. 3538-3550 ◽  
Author(s):  
Chichuan Jin ◽  
Chris Done ◽  
Martin Ward
Keyword(s):  
High Frequency ◽  
Active Galactic Nucleus ◽  
Periodic Oscillation ◽  
Interesting Phenomenon ◽  
Quasi Periodic Oscillation ◽  
X Ray ◽  
Black Hole Binary ◽  
High Coherence ◽  
Spectral State

ABSTRACT RE J1034+396 is a narrow-line Seyfert 1 galaxy (NLS1) in which the first significant X-ray quasi-periodic oscillation (QPO) in an active galactic nucleus (AGN) was observed in 2007. We report the detection of this QPO in a recent XMM–Newton observation in 2018 with an even higher significance. The quality factor of this QPO is 20, and its period is 3550 ± 80 s, which is 250 ± 100 s shorter than in 2007. While the QPO’s period has no significant energy dependence, its fractional root mean square variability increases from 4 per cent in 0.3–1 keV to 12 per cent in 1–4 keV bands. An interesting phenomenon is that the QPO in 0.3–1 keV leads that in the 1–4 keV bands by 430 ± 50 s with a high coherence, opposite to the soft X-ray lag reported for the observation in 2007. We speculate that the QPO has an intrinsic hard lag, while the previous reported soft lag is caused by the interference of stochastic variability. This soft X-ray lead in the new data supports the idea that the QPO of RE J1034+396 is a possible AGN counterpart of the 67 Hz high-frequency QPO seen in the black hole binary GRS 1915+105. We also search for QPO harmonics, but do not find any significant signals. Our new data reinforce previous results that the QPO is seen in a specific spectral state, as the only two observations showing no significant QPO signal exhibit an even stronger soft X-ray excess than the other six observations that display the QPO. Therefore, our results imply that the QPO in RE J1034+396 is physically linked to a soft X-ray component.

scholarly journals DETECTION OF A POSSIBLE X-RAY QUASI-PERIODIC OSCILLATION IN THE ACTIVE GALACTIC NUCLEUS 1H 0707–495

2016 ◽  
Vol 819 (2) ◽  
pp. L19 ◽  
Author(s):  
Hai-Wu Pan ◽  
Weimin Yuan ◽  
Su Yao ◽  
Xin-Lin Zhou ◽  
Bifang Liu ◽  
...  
Keyword(s):  
Active Galactic Nucleus ◽  
Periodic Oscillation ◽  
Quasi Periodic Oscillation ◽  
X Ray

scholarly journals Nonlinear Oscillation of the Magnetosphere around Neutron Stars

1988 ◽  
Vol 108 ◽  
pp. 242-243
Author(s):  
Hitoshi Hanami
Keyword(s):  
Neutron Star ◽  
Angular Velocity ◽  
Neutron Stars ◽  
Nonlinear Oscillation ◽  
Accretion Rate ◽  
Chaotic Oscillation ◽  
Periodic Oscillation ◽  
Unsteady Motion ◽  
Quasi Periodic Oscillation ◽  
X Ray

SummaryWe investigate the unsteady motion of mass reservoir formed by the accretion onto the magnetosphere around rotating neutron stars. The unsteady motion of the reservoir induces secondary accretion to neutron star by R-T instability. The nonperiodic or quasiperiodic phenomena of X-ray bursters seems to be related to this property of mass reservoir on the magnetosphere. We classify the typical dynamical state of the reservoir into three types with the parameters which are accretion rate acc and angular velocity of neutron star Ωs. They are nonsequential oscillation, sequential periodic (quasi-periodic) oscillation, and chaotic oscillation states.

Discovery of an ∼7 H[CLC]z[/CLC] Quasi-periodic Oscillation in the Low-Luminosity Low-Mass X-Ray Binary 4U 1820−30

1999 ◽  
Vol 512 (1) ◽  
pp. L39-L42 ◽  
Author(s):  
Rudy Wijnands ◽  
Michiel van der Klis ◽  
Erik-Jan Rijkhorst
Keyword(s):  
Periodic Oscillation ◽  
Quasi Periodic Oscillation ◽  
X Ray ◽  
Low Mass

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.

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