Relative time delay in a spinning black hole as a diagnostic for no-hair theorem

Izmailov, R. N.; Zhdanov, E. R.; Bhadra, Arunava; Nandi, K. K.

doi:10.1140/epjc/s10052-019-6618-6

Cited by 12 publications

(5 citation statements)

References 36 publications

(73 reference statements)

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“…In the present work, in order to obtain a more comprehensive picture of the photons coupled to the Weyl tensor in the regular phantom black hole, we investigate its time delay in both weak and strong deflection gravitational lensing, which is absent in the previous work [88]. These time-domain signals are important for determining the properties of black holes [89][90][91][92][93][94] and probing new physics [95][96][97][98][99][100][101][102].…”

Section: Introductionmentioning

confidence: 98%

Time delay of photons coupled to Weyl tensor in a regular phantom black hole

Xie

2020

Eur. Phys. J. C

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Time delay of the photons coupled to the Weyl tensor in a regular phantom black hole is investigated in both weak and strong deflection gravitational lensing. We find that the time delay in the weak deflection lensing strongly depends on the phantom hair while the delay in the strong deflection lensing is significantly affected by the hair and the strength of the coupling. We suggest that it is necessary to measure these two kind of time signals for fully understanding and distinguishing such an interaction beyond the standard Einstein–Maxwell theory.

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Section: Introductionmentioning

confidence: 98%

Time delay of photons coupled to Weyl tensor in a regular phantom black hole

Xie

2020

Eur. Phys. J. C

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“…A pulsar closely orbiting SgrA * would also enable to improve the accuracy of its mass estimate, its spin magnitude and its corresponding orientation Liu et al (2012), Zhang & Saha (2017). Furthermore, it offers the possibility for the first time to test the no-hair theorem as well as the cosmic censorship conjecture Liu et al (2012), Christian et al (2015), Izmailov et al (2019) In the usual binary systems the pulsar and the companion have almost the same mass. However in the considered system the mass ratio is extreme what allows a pulsar orbit very close to the supermassive black hole and with a period of only a few years.…”

Section: Introductionmentioning

confidence: 99%

Relativistic propagation and frame dragging time delay in the timing of a pulsar orbiting the supermassive black hole SgrA*

Ben-Salem¹,

Hackmann²

2022

Preprint

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Timing a pulsar in a close orbit around the supermassive black hole SgrA * at the center of the Milky Way would open the window for an accurate determination of the black hole parameters and for new tests of General Relativity and alternative modified gravity theories. An important relativistic effect which has to be taken into account in the timing model is the propagation delay of the pulses in the gravitational field of the black hole. Due to the extreme mass ratio of the pulsar and the supermassive back hole we use the test particle limit to derive an exact analytical formula for the propagation delay in a Kerr spacetime and deduce a relativistic formula for the frame dragging effect on the arrival time. As an illustration, we treat an edge-on orbit in which the frame dragging effect is expected to be maximal. We compare our formula for the propagation time delay with Post-Newtonian approaches, and in particular with the frame dragging terms derived in previous works by Wex & Kopeikin and Rafikov & Lai. Our approach correctly identifies the asymmetry of the frame dragging delay with respect to superior conjunction, avoids singularities in the time delay, and indicates that in the Post-Newtonian approach frame dragging effects are generally slightly overestimated.

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“…A potential example of RTD could be the early observation of extremely rapid fluctuations in the brightness of quasar 1525 + 227 with characteristic time scale ∼ 200 sec speculated to be caused by a spinning black hole of mass M ∼ 5 × 10 8 M ⊙ situated between the quasar and the observer [12]. Recently, RTD has been studied for the Johannsen metric [13] as a possible observable diagnostic to 2 For a true gravitational Bohm-Aharonov effect, see [10]. test the validity of the so-called "no-hair" conjecture of Penrose [14], which broadly states that only mass, electric charge and spin survive the collapse of baryonic matter to a black hole with the other degrees of freedom radiated away.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

String effect on the relative time delay in the Kerr–Sen black hole

et al. 2020

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A well known solution of heterotic string theory is the spinning Kerr-Sen black hole (KSBH) characterized by a string parameter ξ. Kerr black hole is recovered at ξ = 0. The purpose of this paper is to investigate the effect of ξ on a new diagnostic of relative time delay (RTD) to see how the latter deviates from that in general relativity. Assuming KSBH as the spinning lens partner in PSR-BH binary systems, which provide the best laboratory for testing the time delay predictions, we study here the RTD up to third PPN order in (1/r) in the thin-lens approximation. We work out a useful generalization of the RTD formulas applicable to the experimentally viable finite distance lens scales, while terms higher than the zeroth order are shown to contain the effect of ξ. We shall also relate RTD to the observable image magnification factor determined by β/θ E , where β is the angular separation between the source and the observer and θ E is the "Einstein angle" determined by an "effective" non-aligned static lens equivalent to the original aligned spinning lens. Numerical estimates for two typical binary lens systems show µsec level delay at the zeroth order consistent with predictions in the literature. However, the string effect at higher orders is too tiny to be measurable even in the far future leading to the conclusion that the stringy and general relativity BHs are yet observationally indistinguishable.

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Relative time delay in a spinning black hole as a diagnostic for no-hair theorem

Cited by 12 publications

References 36 publications

Time delay of photons coupled to Weyl tensor in a regular phantom black hole

Time delay of photons coupled to Weyl tensor in a regular phantom black hole

Relativistic propagation and frame dragging time delay in the timing of a pulsar orbiting the supermassive black hole SgrA*

String effect on the relative time delay in the Kerr–Sen black hole

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