Deflection angle, quasinormal modes and optical properties of a de Sitter black hole in <math altimg="si6.svg" display="inline" id="d1e1404"><mi>f</mi></math> (<math altimg="si7.svg" display="inline" id="d1e1409"><mi mathvariant="script">T</mi></math>, <math altimg="si8.svg" display="inline" id="d1e1414"><mi mathvariant="script">B</mi></math>) gravity

Parbin, Nashiba; Gogoi, Dhruba Jyoti; Bora, Jyatsnasree; Goswami, Umananda Dev

doi:10.1016/j.dark.2023.101315

Deflection angle, quasinormal modes and optical properties of a de Sitter black hole in $f$ ( $T$ , $B$ ) gravity

Nov 4, 2022

22 pages

Published in:

Phys.Dark Univ. 42 (2023) 101315

Published: Aug 19, 2023

e-Print:

2211.02414 [gr-qc]

DOI:

10.1016/j.dark.2023.101315 (publication)

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Abstract: (Elsevier B.V.)

The current study aims to examine the impact of the boundary term on the bending angle of light for a static spherically symmetric black hole in the modified gravity described by the

f (T, B)

function. To accomplish this objective, we employ the Ishihara et al. method, which enables us to compute the deflection angle of light for a receiver and source situated at finite distances from a lens object in a non-asymptotically flat spacetime. This method considers the receiver’s viewpoint, and the resulting deflection angle diverges as the distance from the lens object increases, owing to the non-asymptotically flat spacetime. Nevertheless, the divergence can be regulated by the boundary term parameter

c_{0}

. For lower values of the parameter

c_{0}

, the divergence can be minimized within the finite range of the observer and source. Furthermore, we calculate the quasinormal modes of massless scalar perturbations in the black hole’s background using the asymptotic iteration method (AIM) and Padé averaged sixth-order Wentzel–Kramers–Brillouin (WKB) approximation method. Our findings indicate that the real quasinormal modes and damping rates are significantly impacted by the model parameter

c_{0}

. Subsequently, we investigate two optical characteristics of the black hole, namely the shadow and the emission rate. Our results show that with an increase in the boundary term parameter

c_{0}

, both the shadow’s size and the evaporation rate decrease.

Note:

22 pages, 9 figures; the published version in Physics of the Dark Universe

Modified gravity
Modified Gravity
Deflection angle
Quasinormal modes
Black hole shadow and emission rate
Black holes
perturbation: gravitation
black hole: quasinormal mode
gravitation: model
black hole: de Sitter

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Deflection angle, quasinormal modes and optical properties of a de Sitter black hole in f (T, B) gravity

Citations per year

Deflection angle, quasinormal modes and optical properties of a de Sitter black hole in $f$ ( $T$ , $B$ ) gravity