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

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.

scholarly journals Epicyclic Oscillations around Simpson–Visser Regular Black Holes and Wormholes

Universe ◽  
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.

scholarly journals X-ray variability of 104 active galactic nuclei

2012 ◽  
Vol 8 (S290) ◽  
pp. 37-40
Author(s):  
O. González-Martín ◽  
S. Vaughan
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Power Law ◽  
Galactic Nuclei ◽  
Power Law Model ◽  
Black Hole Mass ◽  
Periodic Oscillations ◽  
Fundamental Plane ◽  
X Ray ◽  
Single Power

AbstractWe have performed a uniform analysis of the power spectrum densities (PSDs) of 104 nearby (z<0.4) active galactic nuclei (AGN) using 209 XMM-Newton/pn observations, including several AGN classes. These PSDs span ≃ 3 decades in temporal frequencies, ranging from minutes to days. We have fitted each PSD to two models: (1) a single power-law model and (2) a bending power-law model. A fraction of 72% show significant variability. The PSD of the majority of the variable AGN was well described by a simple power-law with a mean index of α = 2.01±0.01. In 15 sources we found that the bending power law model was preferred with a mean slope of α = 3.08±0.04 and a mean bend frequency of 〈νb〉 ≃ 2 × 10−4 Hz. Only KUG 1031+398 (RE J1034+396) shows evidence for quasi-periodic oscillations. The ‘fundamental plane’ relating variability timescale, black hole mass, and luminosity is demonstrated using the new X-ray timing results presented here together with a compilation of the previously detected timescales from the literature.

scholarly journals Confronting the Models of 3 : 2 QPOs with the Evidence of Near Extreme Kerr Black Hole

2012 ◽  
Vol 8 (S290) ◽  
pp. 239-240
Author(s):  
Andrea Kotrlová ◽  
Gabriel Török ◽  
Eva Šrámková ◽  
Zdeněk Stuchlík
Keyword(s):  
Black Hole ◽  
High Frequency ◽  
Kerr Black Hole ◽  
Black Hole Mass ◽  
Tidal Disruption ◽  
Periodic Oscillations ◽  
Rotating Black Hole ◽  
Spectral Fitting ◽  
Generic Problem ◽  
The Individual

AbstractThe black hole mass and spin estimates assuming various specific models of the 3 : 2 high frequency quasi-periodic oscillations (HF QPOs) have been carried out in Török et al. (2005, 2011). Here we briefly summarize some current points. Spectral fitting of the spin a ≡ cJ/GM2 in the microquasar GRS 1915 + 105 reveals that this system can contain a near extreme rotating black hole (e.g., McClintock et al., 2011). Confirming the high value of the spin would have significant consequences for the theory of the HF QPOs. The estimate of a > 0.9 is almost inconsistent with the relativistic precession (RP), tidal disruption (TD), and the warped disc (WD) model. The epicyclic resonance (Ep) and discoseismic models assuming the c- and g- modes are instead favoured. However, consideration of all three microquasars that display the 3 : 2 HF QPOs leads to a serious puzzle because the differences in the individual spins, such as a = 0.9 compared to a = 0.7, represent a generic problem almost for any unified orbital 3:2 QPO model.

scholarly journals Quasi-periodic oscillations around Kerr-MOG black holes

2020 ◽  
Vol 80 (2) ◽  
Author(s):  
Martin Kološ ◽  
Misbah Shahzadi ◽  
Zdeněk Stuchlík
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
High Frequency ◽  
Stellar Mass ◽  
Tidal Disruption ◽  
Periodic Oscillations ◽  
X Ray ◽  
Strong Gravity ◽  
Modified Theory Of Gravity ◽  
Modified Theory

Abstract The study of the quasi-periodic oscillations (QPOs) of X-ray flux observed in the stellar-mass black hole (BH) binaries can provide a powerful tool for testing the phenomena occurring in strong gravity regime. We thus present and apply to three known microquasars the model of epicyclic oscillations of Keplerian discs orbiting rotating BHs governed by the modified theory of gravity (MOG). We show that the standard geodesic models of QPOs can explain the observationally fixed data from the three microquasars, GRO 1655-40, XTE 1550-564, and GRS 1915+105. We perform a successful fitting of the high frequency (HF) QPOs observed in these microquasars, under assumption of MOG BHs, for 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 mass and spin and parameter $$\alpha $$α of the BH.

scholarly journals Disk Oscillations as the Origin of Quasi-Periodic Oscillations in Black Hole Candidates

1998 ◽  
Vol 188 ◽  
pp. 381-381
Author(s):  
T. Yamasaki ◽  
S. Mineshige ◽  
S. Kato
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Galactic Nuclei ◽  
Linear Analysis ◽  
High State ◽  
Periodic Oscillations ◽  
X Ray ◽  
Very High ◽  
Black Hole Candidates

Quasi-periodic oscillations (QPOs) of a few Hz are observed in the very high state of some black hole candidates (GX 339-4 and GS 1124-68). This is the Kepler frequency at the radius of a few hundred Schwarzschild radii. As a possible mechanism of the QPOs in these objects, the trapped oscillations in the accretion disks are considered. The trapped oscillations of the disks were investigated by several authors. They studied the trapped oscillations in the standard radiative cooling-dominated disks. Recently, the advection-dominated accretion flow is considered, as a possible model to explain the hard X-ray spectra of the black hole candidates or the active galactic nuclei. In particular, in the very high state of some black hole candidates, the spectrum can be explained by the disk-corona model which comprises the cold standard accretion disk and the advection-dominated corona above the cold disk. We thus investigated the trapped axi-symmetric oscillations in the advection-dominated corona by the global linear analysis.

Central Black Hole Masses in Active Galactic Nuclei Inferred from X‐Ray Variability

1998 ◽  
Vol 500 (2) ◽  
pp. 642-659 ◽  
Author(s):  
Kiyoshi Hayashida ◽  
Sigenori Miyamoto ◽  
Shunji Kitamoto ◽  
Hitoshi Negoro ◽  
Hajime Inoue
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Central Black Hole ◽  
X Ray ◽  
Black Hole Masses

scholarly journals Supermassive black holes surrounded by dark matter modeled as anisotropic fluid: epicyclic oscillations and their fitting to observed QPOs

2021 ◽  
Vol 2021 (11) ◽  
pp. 059
Author(s):  
Z. Stuchlík ◽  
J. Vrba
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Anisotropic Fluid ◽  
Physical Parameters ◽  
Black Hole Spacetimes ◽  
Test Particles

Abstract Recently introduced exact solution of the Einstein gravity coupled minimally to an anisotropic fluid representing dark matter can well represent supermassive black holes in galactic nuclei with realistic distribution of dark matter around the black hole, given by the Hernquist-like density distribution. For these fluid-hairy black hole spacetimes, properties of the gravitational radiation, quasinormal ringing, and optical phenomena were studied, giving interesting results. Here, using the range of physical parameters of these spacetimes allowing for their relevance in astrophysics, we study the epicyclic oscillatory motion of test particles in these spacetimes. The frequencies of the orbital and epicyclic motion are applied in the epicyclic resonance variant of the geodesic model of quasiperiodic oscillations (QPOs) observed in active galactic nuclei to demonstrate the possibility to solve the cases where the standard vacuum black hole spacetimes are not allowing for explanation of the observed data. We demonstrate that the geodesic model can explain the QPOs observed in most of the active galactic nuclei for the fluid-hairy black holes with reasonable halo parameters.

scholarly journals Radiative efficiency of hot accretion flow and the radio/X-ray correlation in X-ray binaries

2014 ◽  
Vol 10 (S312) ◽  
pp. 139-140
Author(s):  
Fu-Guo Xie
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Accretion Rate ◽  
Galactic Nuclei ◽  
X Ray ◽  
Radiative Efficiency ◽  
Accretion Flow ◽  
Accretion Rates ◽  
Distinctive Property ◽  
X Ray Binaries

AbstractSignificant progresses have been made since the discovery of hot accretion flow, a theory successfully applied to the low-luminosity active galactic nuclei (LLAGNs) and black hole (BH) X-ray binaries (BHBs) in their hard states. Motivated by these updates, we re-investigate the radiative efficiency of hot accretion flow. We find that, the brightest regime of hot accretion flow shows a distinctive property, i.e. it has a constant efficiency independent of accretion rates, similar to the standard thin disk. For less bright regime, the efficiency has a steep positive correlation with the accretion rate, while for faint regime typical of advection-dominated accretion flow, the correlation is shadower. This result can naturally explain the observed two distinctive correlations between radio and X-ray luminosities in black hole X-ray binaries. The key difference in systems with distinctive correlations could be the viscous parameter, which determines the critical luminosity of different accretion modes.

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