Shadow cast by Kerr-like black hole in the presence of plasma in Einstein-bumblebee gravity

Abstract

In the Einstein-bumblebee gravity, the Lorentz symmetry is spontaneously broken by a vector field.In this paper, we attempt to test the Lorentz symmetry via the observation of the shadow cast by the Kerr-like black hole with or without plasma. A novel phenomenon of the Lorentz-violating parameter on the shadow is observed. The result shows that when the observer gradually moves from the poles to the equatorial plane, the shadow radius Rs firstly decreases and then increases with the Lorentzviolating parameter. Such nonmonotonic behavior provides us an important understanding on the black hole shadow in the Einstein-bumblebee gravity. Besides, three more distortion observables are calculated, and found to increase with the Lorentz-violating parameter. Moreover, when a homogeneous plasma is present, the motion of the photon is analyzed. We further observe that the refractive index shrinks the size, while enhances the deformation of the shadow. Finally, adopting the observed data of the diameter of M87 * , we find the refractive index is more favored in (0.914, 1).

Reply to "Comment on 'Greybody radiation and quasinormal modes of Kerr-like black hole in Bumblebee gravity model' "

“…In conclusion, the above consideration shows that although the metric solution provided by Ding et al [2] and which we also used it in our recent study [1] like the others [4][5][6][7] is incorrect, the GF and QNM results obtained in [1] can be adopted for metric (8) (with ã → a), which represents the slowly rotating Kerr-like black hole solution to the Einsteinbumblebee gravity equations [9]. Besides, we want to emphasize that our GFs and QNMs analyzes in general do not strongly depend on the type of metrics.…”

“…In fact, we did the GF and QNM studies with high confidence, based on Ding et al's paper [2], as the supposed new Kerr-like black hole solution has passed the serious peer-reviews of one of the most respected journals in the world. Similar to us, in the recent past, it is possible to see that there are many quality studies that have directly used that black hole solution (see for example [4][5][6][7]).…”

No-Hair Theorem in the Wake of Event Horizon Telescope

“…With the advent of EHT, has been revived a great deal of interest in computing the shadows associated with the extensive class of BH solutions, mostly come from extended gravity theories, non-linear electrodynamics regimes, new physics and etc [52]- [74]. In some studies have tried to shining light on hot issues such as dark energy and dark matter, via matching the BH surrounded by some matter fields with the extracted information from the EHT image of M87* BH shadow [75]- [86].…”

Axion-plasmon or magnetized plasma effect on an observable shadow and gravitational lensing of a Schwarzschild black hole

“…However, the photon trajectory would be quite different in vacuum and in a dense electrically charged medium such as a plasma near a BH [32,33]. It has been reported several times with different models in the scientific literature [34][35][36][37][38][39][40][41] that the plasma surrounding a BH forces light to bend further i.e. α tot = α BH + α plasma , which represents the contributions to the total deflection angle due to a BH and plasma separately.…”