Quasi-periodic oscillations around Kerr-MOG black holes

Kološ, Martin; Shahzadi, Misbah; Stuchlík, Zdeněk

doi:10.1140/epjc/s10052-020-7692-5

Cited by 45 publications

(13 citation statements)

References 50 publications

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“…Unfortunately, none of the models recently discussed in literature, based on the frequencies of the harmonic geodesic epicyclic motion, is able to explain the HF QPOs in quasars and all four microquasars simultaneously, assuming that their central attractor is a BH [7,28]. One of the most promising ways of explaining these QPO phenomena in quasars and microquasars could be charged particle oscillations around magnetized BHs [8,9,29,30].…”

Section: Quasi-periodic Oscillations Modelsmentioning

confidence: 99%

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

Shahzadi,

Kološ,

Stuchlík

et al. 2021

Preprint

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The 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 quasars as well as microquasars 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 quasars and microquasars 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 S of the test particle, mass M and spin a of the BH.

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Section: Quasi-periodic Oscillations Modelsmentioning

confidence: 99%

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

Shahzadi,

Kološ,

Stuchlík

et al. 2021

Preprint

Self Cite

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“…The Ref [13] has been devoted to study the epicyclic frequencies in Kerr-MOG black hole. Quasi-periodic oscillations around Kerr-MOG black holes have been considered in [14]. Authors of [15] have studied the test particle dynamics near Kerr-MOG black hole.…”

Section: Introductionmentioning

confidence: 99%

Weak gravitational lensing Schwarzschild-MOG black hole in plasma

2021

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This paper is devoted to study weak gravitational lensing properties around black hole surrounded plasma medium in modified gravity (MOG). We have investigated the effects of the MOG-parametr and plasma medium on the deflection angle and total magnification of the images. we have presented the comparisons of the effects of the uniform plasma, singular isothermal sphere and non-singular isothermal sphere. We have also shown that the uniform plasma effects significantly stronger than the other models of plasma medium.Through the studies of the total magnifications of images of a remote source we have shown that the effects of the MOG parameter and plasma medium are similar and the increase of the MOG parameter and plasma frequency cause to increase the total magnification. Moreover, we have explored and analyzed how the MOG effects can reflect the plasma medium providing the same values of the total magnification of images.

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“…QPOs are useful for testing both accretion matter physics and the nature of gravitational interaction in the strong-field regime. Accretion disc surrounding BH as a source of QPO in different models has been widely discussed in the literature [48][49][50][51][52][53][54][55][56][57]. Particularly, various models explaining the qualitative behaviour of the QPO including disc-seismic models, hot-spot models, warped disk models, and resonance models have been proposed [50,[58][59][60].…”

Section: Introductionmentioning

confidence: 99%

Dynamics of Test Particles and Twin Peaks QPOs around Regular Black Holes in Modified Gravity

et al. 2021

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In this work, we have presented a detailed analysis of the event horizon of regular black holes (BHs) in modified gravity known as MOG, the so-called regular MOG BH. The motion of neutral particles around the BH has also been explored. The test particle motion study shows that the positive (negative) values of the MOG parameter mimic the spin of a rotating Kerr BH, providing the same values for the innermost stable pro-grade (retrograde) orbits of the particles in the range of the spin parameter a/M∈(−0.4125,0.6946). The efficiency of energy release from the accretion disk by the Novikov–Thorne model has been calculated, and the efficiency was shown to be linearly proportional to the increase of the MOG parameter α. Moreover, we have developed a new methodology to test gravity theories in strong-field regimes using precision data from twin-peaked quasiperiodic oscillations (QPOs) of objects calculating possible values of upper and lower frequencies. However, it is obtained that the positive MOG parameter can not mimic the spin of Kerr BHs in terms of the same QPO frequencies. We have provided possible ranges for upper and lower frequencies of twin-peak QPOs with the ratio of the upper and lower frequencies of 3:2 around regular MOG BHs in the different models. Moreover, as an example, we provide detailed numerical analysis of the QPO of GRS 1915+105 with the frequencies νU=168±5Hz and νL=113±3Hz. It is shown that the central BH of the QPO object can be a regular MOG BH when the value of the parameter is α=0.2844−0.1317+0.0074 and shines in the orbits located at the distance r/M=7.6322−0.0826+0.0768 from the central BH. It is also shown that the orbits where QPOs shine are located near the innermost stable circular orbit (ISCO) of the test particle. The correlation between the radii of ISCO and the QPO orbits is found, and it can be used as a new theoretical way to determine ISCO radius through observational data from the QPOs around various compact objects.

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Quasi-periodic oscillations around Kerr-MOG black holes

Cited by 45 publications

References 50 publications

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

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

Weak gravitational lensing Schwarzschild-MOG black hole in plasma

Dynamics of Test Particles and Twin Peaks QPOs around Regular Black Holes in Modified Gravity

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