Shadows and strong gravitational lensing: a brief review

Cunha, Pedro V. P.; Herdeiro, Carlos

doi:10.1007/s10714-018-2361-9

Cited by 451 publications

(309 citation statements)

References 114 publications

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“…Analytical calculation of the shadow size and shape in vacuum for Kerr metric was first done by J.M. Bardeen [1], for the observer far away from BH, see Fig.4, [10], [27], [4].…”

Section: What Is a Black Hole Shadowmentioning

confidence: 99%

Shadow of a black hole at cosmological distances

2018

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A brief illustrative discussion of the shadows of black holes at local and cosmological distances is presented. Starting from definition of the term and discussion of recent observations, we then investigate shadows at large, cosmological distances. On a cosmological scale, the size of shadow observed by comoving observer is expected to be affected by cosmic expansion. Exact analytical solution for the shadow angular size of Schwarzschild black hole in de Sitter universe was found.Additionally, an approximate method was presented, based on using angular size redshift relation. This approach is appropriate for general case of any multicomponent universe (with matter, radiation and dark energy). It was shown, that supermassive black holes at cosmological distances in universe with matter may give the shadow size comparable with the shadow size in M87, and in the center of our Galaxy.

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“…Analytical calculation of the shadow size and shape in vacuum for Kerr metric was first done by J.M. Bardeen [1], for the observer far away from BH, see Fig.4, [10], [27], [4].…”

Section: What Is a Black Hole Shadowmentioning

confidence: 99%

Shadow of a black hole at cosmological distances

2018

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“…The influence of the plasma interaction on the gravitational scattering of scalar particles (photons) was extensively studied (see, e.g., Ref. [18] for a review). For example, the photons propagation in plasma surrounding a nonrotating BH was examined in Ref.…”

Section: Discussionmentioning

confidence: 99%

“…The interaction with plasma can modify the size and the form of the BH shadow (see Ref. [18] for a review). In the present work, we shall study how the neutrino interaction with background matter, e.g., with an accretion disk, can influence the observed flux of gravitationally scattered neutrinos.…”

Section: Introductionmentioning

confidence: 99%

Spin effects in neutrino gravitational scattering

Dvornikov

2020

Phys. Rev. D

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We study spin oscillations of neutrinos gravitationally scattered off a nonrotating black hole (BH). We derive the transition and survival probabilities of spin oscillations in quadratures when neutrinos interacts with BH only. The dependence of the probabilities on the impact parameter is analyzed. Then, we obtain the effective Schrödinger equation for neutrino spin oscillations in neutrino scattering off BH surrounded by background matter. This equation is solved numerically in the case of a supermassive BH with a realistic accretion disk. We find that the observed neutrino fluxes can be reduced almost 20% because of spin oscillations when neutrinos experience gravitational scattering. The neutrino interaction with an accretion disk results in the additional asymmetry in the intensities of outgoing fluxes depending on the neutrino trajectory. * maxdvo@izmiran.ru

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“…In particular, for a BH surrounded by a geometrically thick, optically thin emission region, the shadow should be visible as a dark region on the sky, surrounded by a bright emission ring (see e.g. [71][72][73][74][75]). For a Schwarzschild BH, the radius of the shadow r sh = 3 √ 3M ≈ 5.2M is equal neither to the Schwarzschild radius r s = 2M nor to the photon sphere radius r ph = 3M , but is actually slightly larger than both due to the fact that the shadow is the gravitationally lensed image of the photon sphere [71].…”

Section: Black Hole Shadows As Standard Rulersmentioning

confidence: 99%

Concerns regarding the use of black hole shadows as standard rulers

Vagnozzi¹,

Bambi²,

Visinelli³

2020

Class. Quantum Grav.

128

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Recently, Tsupko et al. have put forward the very interesting proposal to use the shadows of highredshift supermassive black holes (SMBHs) as standard rulers. This would in principle allow us to probe the expansion history within a redshift range which would otherwise be challenging to access. In this note, we critically examine this proposal, and identify a number of important issues which had been previously overlooked. These include difficulties in obtaining reliable SMBH mass estimates and reaching the required angular resolution, and an insufficient knowledge of the accretion dynamics of high-redshift SMBHs. While these issues currently appear to prevent high-redshift SMBH shadows from being used as robust standard rulers, we hope that our flagging them early will help in making this probe theoretically mature by the time it will be experimentally feasible.

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Shadows and strong gravitational lensing: a brief review

Cited by 451 publications

References 114 publications

Shadow of a black hole at cosmological distances

Shadow of a black hole at cosmological distances

Spin effects in neutrino gravitational scattering

Concerns regarding the use of black hole shadows as standard rulers

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