Cuspy and fractured black hole shadows in a toy model with axisymmetry

Qian, Wei-Liang; Chen, Songbai; Shao, Cheng-Gang; Wang, Bin; Yue, Rui-Hong

doi:10.48550/arxiv.2102.03820

Cited by 8 publications

(9 citation statements)

References 42 publications

(63 reference statements)

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“…It was shown that discontinuity in the effective potential furnishes a possible origin of black hole echoes [65], which was understood as due to the modification to the pole structure of Green's function. The presence of a dusty thin shell was found to affect the black hole shadow non-trivially [66].…”

Section: Further Discussion and Concluding Remarksmentioning

confidence: 99%

Matrix method for perturbed black hole metric with discontinuity

Shen¹,

Qian²,

Lin³

et al. 2022

Preprint

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Recent studies based on the notion of black hole pseudospectrum indicated substantial instability of the fundamental and high-overtone quasinormal modes. Besides its theoretical novelty, the details about the migration of the quasinormal mode spectrum due to specific perturbations may furnish valuable information on the properties of associated gravitational waves in a more realistic context. This work generalizes the matrix method for black hole quasinormal modes to cope with a specific class of perturbations to the metric featured by discontinuity, which is known to be intimately connected with the quasinormal mode structural instability. In practice, the presence of discontinuity poses a difficulty so that many well-known approaches for quasinormal modes cannot be straightforwardly applied. By comparing with other methods, we show that the modified matrix method is efficient, which can be used to solve for the low-lying modes with reasonable precision. Therefore, it might serve as an alternative gadget for relevant studies.

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Section: Further Discussion and Concluding Remarksmentioning

confidence: 99%

Matrix method for perturbed black hole metric with discontinuity

Shen¹,

Qian²,

Lin³

et al. 2022

Preprint

Self Cite

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show abstract

“…Recently, many exciting features of the black hole shadow have received much attention. Intriguing speculations include cuspy [29,30], fractured [30], and open [31] shadows. In particular, the black hole shadow has also been analyzed from the viewpoint of dynamical system [32].…”

Section: Further Discussion and Concluding Remarksmentioning

confidence: 99%

Quasinormal modes in two-photon autocorrelation and the geometric-optics approximation

et al. 2022

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In this work, we study the black hole light echoes in terms of the two-photon autocorrelation and explore their connection with the quasinormal modes. It is shown that the above time-domain phenomenon can be analyzed by utilizing the well-known frequency-domain relations between the quasinormal modes and characteristic parameters of null geodesics. We found that the time-domain correlator, obtained by the inverse Fourier transform, naturally acquires the echo feature, which can be attributed to a collective effect of the asymptotic poles through a weighted summation of the squared modulus of the relevant Green’s functions. Specifically, the contour integral leads to a summation taking over both the overtone index and angular momentum. Moreover, the dominant contributions to the light echoes are from those in the eikonal limit, consistent with the existing findings using the geometric-optics arguments. For the Schwarzschild black holes, we demonstrate the results numerically by considering a transient spherical light source. Also, for the Kerr spacetimes, we point out a potential difference between the resulting light echoes using the geometric-optics approach and those obtained by the black hole perturbation theory. Possible astrophysical implications of the present study are addressed.

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“…( 1), the feasibility of separation of variable implies that such geodesics are spherical 1 . Subsequently, the boundary of black holes shadow is mostly determined by the unstable photon orbits around the black hole, except for the metastable ones [40]. Indeed, when perturbed, the 1) as functions of the radius coordinate r, which in turn determine the horizon and ergoregion.…”

Section: Photon Regionmentioning

confidence: 99%

Shadows of magnetically charged rotating black holes surrounded by quintessence

Sun,

Liu,

Qian

et al. 2022

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In this work, we study the optical properties of a class of magnetically charged rotating black hole spacetimes. The black holes in question are assumed to be immersed in the quintessence field, and subsequently, the resulting black hole shadows are expected to be modified by the presence of the dark energy. We investigate the photon region and the black hole shadow, and in particular, their dependence on the relevant physical conditions such as the state parameter of the quintessence, the angular momentum, and the magnitude of the magnetic charge. It is shown that the photon regions sensitively depend on the horizon structure and possess intricate features. Moreover, from the viewpoint of a static observer, we explore a few observables, especially those associated with the distortion of the observed black hole shadows.

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Cuspy and fractured black hole shadows in a toy model with axisymmetry

Cited by 8 publications

References 42 publications

Matrix method for perturbed black hole metric with discontinuity

Matrix method for perturbed black hole metric with discontinuity

Quasinormal modes in two-photon autocorrelation and the geometric-optics approximation

Shadows of magnetically charged rotating black holes surrounded by quintessence

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