Light from Schwarzschild black holes in de Sitter expanding universe

Cotăescu, Ion I.

doi:10.1140/epjc/s10052-020-08822-x

Cited by 9 publications

(2 citation statements)

References 51 publications

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“…( 49) and (51) for , verifying that for closing again the identity (45). Note that the relation among the conserved quantities and can be derived directly according to the transformation rule under isometries we have discussed recently [18,19].…”

Section: B Time-like Geodesicsmentioning

confidence: 99%

Kinemaitcs in spatially flat FLRW spacetimes

Cotăescu¹

2021

Chinese Phys. C

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New conserved spin and orbital angular momentum operators of Dirac's theory on spatially flat FLRW spacetimes are proposed generalizing thus recent results concerning the role of Pryce's spin operator in the flat case [I. I. Cotȃescu, Eur. Phys. J. C (2022) 82:1073]. These operators split the conserved total angular momentum generating the new spin and orbital symmetries that form the rotations of the isometry groups. The new spin operator is defined and studied in active mode with the help of a suitable spectral representation giving its Fourier transfor. Moreover, in the same manner is defined the operator of the fermion polarization. The orbital angular momentum is derived in passive mode using a new method, inspired by Wigner's theory of induced representations, but working properly only for global rotations. In this approach the quantization is performed finding that the one-particle spin and orbital angular momentum operators have the same form in any FLRW spacetime regardless their concrete geometries given by various scale factors.

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Section: B Time-like Geodesicsmentioning

confidence: 99%

Kinemaitcs in spatially flat FLRW spacetimes

Cotăescu¹

2021

Chinese Phys. C

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“…Besides a general transformation as proposed in [49] can transform the Kottler metric to the FLRW metric where the expansion is driven by the cosmological constant Λ. Some recent works related to the case of expanding Universe can be found in [50][51][52][53][54][55][56][57].…”

Section: Introductionmentioning

confidence: 99%

Shadow of Kottler black hole in the presence of plasma for a co-moving observer

Das¹,

Gangopadhyay²

2022

Class. Quantum Grav.

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In this paper, we discussed the shadow of a static, spherically symmetric black hole geometry in presence of a positive cosmological constant $\Lambda >0$. We analysed the black hole shadow both in absence and presence of plasma. Then we study the black hole shadow from the point of view of a comoving observer. We display the plots for the angular shadow size as measured by a comoving observer. The effects of the cosmological constant $\Lambda$ and plasma parameter $k$ on the angular size of the black hole shadow have been investigated in detail. Finally, by using the observed angular size of M87$^*$ and Sgr A$^*$ black hole, we constrain the value of the plasma parameter $k$ with a specific observational value of the cosmological constant $\Lambda$ (or the Hubble constant $H_0$).

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QED effect on a black hole shadow

Zhong

et al. 2021

Phys. Rev. D

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Light from Schwarzschild black holes in de Sitter expanding universe

Cited by 9 publications

References 51 publications

Kinemaitcs in spatially flat FLRW spacetimes

Kinemaitcs in spatially flat FLRW spacetimes

Shadow of Kottler black hole in the presence of plasma for a co-moving observer

QED effect on a black hole shadow

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