The optical appearance of charged four-dimensional Gauss–Bonnet black hole with strings cloud and non-commutative geometry surrounded by various accretions profiles

Abstract

Thanks for the releasing image of supermassive black holes (BHs) by the event horizon telescope (EHT) at the heart of the M87 galaxy. After the discovery of this mysterious object, scientists paid attention to exploring the BH shadow features under different gravitational backgrounds. In this scenario, we study the light rings and observational properties of BH shadow surrounded by different accretion flow models and then investigate the effect of model parameters on the observational display and space-time structure of BHs in the framework of our considering system. Under the incompatible configuration of the emission profiles, the images of BHs comprise that the observed luminosity is mainly determined by direct emission, while the lensing ring will provide a small contribution of the total observed flux and the photon ring makes a negligible contribution due to its exponential narrowness. More importantly, the observed regions and specific intensities of all emission profiles are changed correspondingly under variations of parameters. For optically thin accreting matters, we analyze the profile and specific intensity of the shadows with static and infalling accretions models, respectively. We find that with an infalling motion the interior region of the shadows will be darker than the static case, due to the Doppler effect of the infalling movement. Finally, it is concluded that these findings support the fact that the change of BH state parameters will change the way of space-time geometry, thus affecting the BH shadow dynamics.

Shadow images of compact objects in beyond Horndeski theory

“…On the other hand, theoretical investigations of shadow images of compact objects are quite fascinating. This applies not only to black holes in General Relativity [36][37][38][39][40][41][42][43][44][45] and in alternative gravities [46][47][48][49][50][51][52][53][54][55][56], but also to exotic compact objects like wormholes [57][58][59][60][61][62][63][64][65][66][67], naked singlarities [68][69][70][71][72][73][74][75][76][77][78] or boson stars [79,80]. Previous studies have shown that some of these exotic compact objects can mimic black holes with respect to their shadow images if their light ring properties are similar.…”

Holographic Einstein rings of an AdS black hole in massive gravity

“…This makes it feasible to analyze the observational characteristics of BH shadows surrounded by different accretion flow models. In the mechanism of different theories, the study of BH shadow and its observational appearance along with other significant properties have also been analyzed in [36][37][38] and many other associated works exist in literature. Nowadays, a number of researchers have devoted themselves to exploring the physics of BH images and trying to achieve remarkable results, which told a comprehensive story of BH in our Universe.…”

Observational signatures of charged rotating traversable wormhole: shadows and light rings with different accretions

“…Assuming an optically thin disk accretion flow model, Gralla et al [20] discussed the BH shadow and the photon rings of Schwarzschild BH and found that the luminosity of the ring diverges logarithmically at the position of the photon ring. Zeng et al [21] analyzed some interesting features of the charged four-dimensional Gauss-Bonnet BH, considering the strings clouds and non-commutative (NC) geometry under different accretions flow models. Saleem and Aslam [22] investigated the optical features of a charged NC Kiselev BH through different configurations of accretion matter.…”