Quasi-Periodic Oscillatory Motion of Particles Orbiting a Distorted, Deformed Compact Object

This work explores the dynamic properties of test particles surrounding a distorted, deformed compact object. The astrophysical motivation was to choose such a background as to constitute a more reasonable model of a real situation that arises in the vicinity of compact objects with the possibility of having parameters such as the extra physical degrees of freedom. This can facilitate associating observational data with astrophysical systems. This work’s main goal is to study the dynamic regime of motion and quasi-periodic oscillation in this background, depending on different parameters of the system. In addition, we exercise the resonant phenomena of the radial and vertical oscillations at their observed quasi-periodic oscillations frequency ratio 3:2 and show that the oscillatory frequencies of charged particles can be adequately related to the frequencies of the twin high-frequency quasi-periodic oscillations observed in some sources of the microquasar observational data.

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Epicyclic Oscillations around Simpson–Visser Regular Black Holes and Wormholes

Universe ◽

10.3390/universe7080279 ◽

2021 ◽

Vol 7 (8) ◽

pp. 279

Author(s):

Zdeněk Stuchlík ◽

Jaroslav Vrba

Keyword(s):

Black Holes ◽

Black Hole ◽

Active Galactic Nuclei ◽

Observational Data ◽

High Frequency ◽

Galactic Nuclei ◽

Supermassive Black Holes ◽

Periodic Oscillations ◽

High Length ◽

Circular Geodesic

We study epicyclic oscillatory motion along circular geodesics of the Simpson–Visser meta-geometry describing in a unique way regular black-bounce black holes and reflection-symmetric wormholes by using a length parameter l. We give the frequencies of the orbital and epicyclic motion in a Keplerian disc with inner edge at the innermost circular geodesic located above the black hole outer horizon or on the our side of the wormhole. We use these frequencies in the epicyclic resonance version of the so-called geodesic models of high-frequency quasi-periodic oscillations (HF QPOs) observed in microquasars and around supermassive black holes in active galactic nuclei to test the ability of this meta-geometry to improve the fitting of HF QPOs observational data from the surrounding of supermassive black holes. We demonstrate that this is really possible for wormholes with sufficiently high length parameter l.

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Epicyclic oscillations in spinning particle motion around Kerr black hole applied in models fitting the quasi-periodic oscillations observed in microquasars and AGNs

The European Physical Journal C ◽

10.1140/epjc/s10052-021-09868-1 ◽

2021 ◽

Vol 81 (12) ◽

Author(s):

Misbah Shahzadi ◽

Martin Kološ ◽

Zdeněk Stuchlík ◽

Yousaf Habib

Keyword(s):

Black Hole ◽

Active Galactic Nuclei ◽

High Frequency ◽

Kerr Black Hole ◽

Galactic Nuclei ◽

Tidal Disruption ◽

Periodic Oscillations ◽

Spinning Particle ◽

X Ray ◽

Test Particles

AbstractThe study of the quasi-periodic oscillations (QPOs) of X-ray flux observed in the stellar-mass black hole (BH) binaries or quasars can provide a powerful tool for testing the phenomena occurring in strong gravity regime. We thus fit the data of QPOs observed in the well known microquasars as well as active galactic nuclei (AGNs) in the framework of the model of geodesic oscillations of Keplerian disks modified for the epicyclic oscillations of spinning test particles orbiting Kerr BHs. We show that the modified geodesic models of QPOs can explain the observational fixed data from the microquasars and AGNs but not for all sources. We perform a successful fitting of the high frequency QPOs models of epicyclic resonance and its variants, relativistic precession and its variants, tidal disruption, as well as warped disc models, and discuss the corresponding constraints of parameters of the model, which are the spin of the test particle, mass and rotation of the BH.

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Numerical Simulations of Advective Flows Around Black Holes

International Astronomical Union Colloquium ◽

10.1017/s025292110004344x ◽

1997 ◽

Vol 163 ◽

pp. 690-691

Author(s):

Sandip K. Chakrabarti ◽

D. Ryu ◽

D. Molteni ◽

H. Sponholz ◽

G. Lanzafame ◽

...

Keyword(s):

Numerical Simulations ◽

Periodic Oscillation ◽

Compact Objects ◽

Advective Flow ◽

Sonic Point ◽

Quasi Periodic Oscillation ◽

Accretion Flows ◽

Advective Flows ◽

Cooling Effects ◽

Implicit Code

Observational results of compact objects are best understood using advective accretion flows (Chakrabarti, 1996, 1997). We present here the results of numerical simulations of all possible types of such flows.Two parameter (specific energy ε and specific angular momentum λ) space of solutions of inviscid advective flow is classified into ‘SA’ (shocks in accretion), ‘NSA’ (no shock in accretion), ‘I’ (inner sonic point only), ‘O’ (outer sonic point only) etc. (Fig. 1 of Chakrabarti, 1997 and references therein). Fig. 1a shows examples of solutions (Molteni, Ryu & Chakrabarti, 1996; Eggum, in preparation) from ‘SA’, ‘I’ and ‘O’ regions where we superpose analytical (solid) and numerical simulations (short dashed curve is with SPH code and medium dashed curve is with TVD code; very long dashed curve is with explicit/implicit code). The agreement is excellent. In presence of cooling effects, shocks from ‘SA’ oscillate (Fig. 1b) when the cooling timescale roughly agrees with postshock infall time scale (Molteni, Sponholz & Chakrabarti, 1996). The solid, long dashed and short dashed curves are drawn for T1/2 (bremsstrahlung), T0.4 and T0.75 cooling laws respectively. In the absence of steady shock solutions, shocks for parameters from ‘NSA’ oscillate (Fig. 2) even in the absence of viscosity (Ryu et al. 1997). The oscillation frequency and amplitude roughly agree with those of quasi-periodic oscillation of black hole candidates. When the flow starts from a cool Keplerian disk, it simply becomes sub-Keplerian before it enters through the horizon. Fig. 3a shows this behaviour where the ratio of λ/λKeplerian is plotted. When the flow deviates from a hot Keplerian disk, it may develop a standing shock as well (Fig. 3b) (Molteni et al. 1996).

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Discovery of a Second High-Frequency Quasi-periodic Oscillation from the Microquasar GRS 1915+105

The Astrophysical Journal ◽

10.1086/321720 ◽

2001 ◽

Vol 554 (2) ◽

pp. L169-L172 ◽

Cited By ~ 100

Author(s):

Tod E. Strohmayer

Keyword(s):

High Frequency ◽

Periodic Oscillation ◽

Quasi Periodic Oscillation

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

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1356 ◽

2020 ◽

Vol 495 (4) ◽

pp. 3538-3550 ◽

Cited By ~ 3

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.

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Possible detection of a new cyclotron feature in 4U 1700–37

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa437 ◽

2020 ◽

Vol 493 (2) ◽

pp. 3045-3053

Author(s):

Suman Bala ◽

Jayashree Roy ◽

Dipankar Bhattacharya

Keyword(s):

Compact Object ◽

Periodic Oscillation ◽

High Mass ◽

Emission Region ◽

Frequency Range ◽

Quasi Periodic Oscillation ◽

X Ray ◽

Line Feature ◽

Transient Source ◽

Cyclotron Line

ABSTRACT We present a spectral and timing study of the high-mass X-ray binary transient source 4U 1700–37 using NuSTAR and ASTROSAT/LAXPC. The source is observed in two different flux states. A combined spectral analysis of NuSTAR’s focal plane modules A and B shows the possible hint of a cyclotron line feature at ∼16 keV. The line feature is consistently present in different continuum models with at least 3σ confidence level. We do not detect the presence of a previously reported 39 keV cyclotron line in the combined spectra. A ∼16 keV cyclotron feature would suggest that the compact object is a neutron star with a magnetic field strength ∼2.1 × 1012 G in the emission region. We also find the presence of a rare Ni Kα emission line around 7.6 keV in the NuSTAR spectrum. We searched the NuSTAR and ASTROSAT data for coherent or quasi-periodic oscillation signals but found no evidence in the frequency range 0.1 mHz to 103 Hz.

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