4D scale-dependent Schwarzschild-AdS/dS black holes: study of shadow and weak deflection angle and greybody bounding

Abstract

We investigate the shadow, deflection angle, and the greybody bounding of a Schwarzschild-AdS/dS black hole in scale-dependent gravity. We used the EHT data to constrain the parameter $$\epsilon$$ ϵ . We have found that within the $$1\sigma$$ 1 σ level of uncertainty, $$\epsilon M_0$$ ϵ M 0 ranges at $$10^{-11} - 10^{-16}$$ 10 - 11 - 10 - 16 orders of magnitude for Sgr. A*, and $$10^{-11} - 10^{-17}$$ 10 - 11 - 10 - 17 for M87*. Using these parameters, we explored how the shadow radius behaves as perceived by a static observer. Using the known parameters for Sgr. A* and M87*, we found different shadow cast behavior near the cosmological horizon even if the same scaling parameters were used. We explored the deflection angle $${\hat{\alpha }}$$ α ^ in the weak field limit for both massive and null particles, in addition to the effect of finite distances using the non-asymptotically flat version of the Gauss-Bonnet theorem. We have found that the $${\hat{\alpha }}$$ α ^ strongly depends on massive particles. Tests on $$\epsilon$$ ϵ ’s effect using Sgr. A* is only along points of low impact parameters. For M87*, only the scaled BH in AdS type can be tested at high impact parameters at the expense of very low value for $${\hat{\alpha }}$$ α ^ . We study the rigorous bound on the greybody factor for scalar field emitted from black holes in the theory and show the bound on the transmission probability. The effects of the scale-dependent gravity on the greybody factors are investigated, and the results indicate that the bound on the greybody factor in this case is less than the bound for the Schwarzschild black hole.

Constraints on charged symmergent black hole from shadow and lensing

“…Many authors have considered the fingerprints of alternative theories of gravity through the shadow , while others explored the effects of the astrophysical environment into the shadow [76][77][78][79][80][81]. Through the black hole shadow, it also can penetrate through its quantum nature [82][83][84][85][86][87][88][89].…”

Microlensing and multi-images problem of static spherical symmetric wormhole

“…In this paper, we will re-examine this problem from a new perspective by implementing the REoS to depict the lensing effects of the spherically symmetric wormhole metric. Then we calculate the deflection angle of this metric by Gauss-Bonnet Theorem (GBT) [53][54][55] which is widely used in gravitational lenses to calculate deflection angle [56][57][58][59][60][61][62][63][64], and we find that the state coefficient η determines the maximum value of the image of a light source in the equatorial plane. In the last section, we discuss the applicability of the image number formula n = 2 + 1 η .…”