Influence of dark matter on shadows and rings of a brane-world black hole illuminated by various accretions

Abstract

In this paper, by taking the accretions into account, the observational shadows and rings casted by the Brane-World black hole are numerically investigated when the observer located at the cosmological horizon. The results here show that the radius r p of photon sphere increased with cosmological parameter α and dark matter parameter β, while the impact parameter b p decreased with α and increased with β. For the thin-disk accretion, it turns out that the total observed intensity are mainly composed of the direct emission, while lensing ring and photon ring only contribute a small contribution and a negligible contribution, respectively. And, we find that shadow and rings exhibit some different and interesting features when the disk located at different positions. For the static and infalling spherical accretions, it is obvious that the size of shadow is always the same for both accretions, which means that shadow is only related to the geometry of space time in this case. The luminosity of shadow and photon sphere are closely related to the Doppler effect and the emissivity per unit volume j(ν e ). In addition, the influence of dark matter and cosmological constant on observed intensity of shadows and rings are carefully emphasized throughout of this paper. Finally, we obtained the burring images of shadows and rings by using the nominal resolution of the Event Horizon Telescope, and studied the upper limits on the X-clod dark matter parameter β with the aid of the data of the shadow of M87.

Black holes surrounded by Einstein clusters as models of dark matter fluid

“…Using the relation between the surface density and the mass of the shell we find that the total mass of the system is given by Eq. (24). Again, the corrections due to the thin shell of matter are very small and the resulting spacetime geometry is asymptotically flat.…”

Rotating black holes with an anisotropic matter field

“…Due to this property, the shape of the capturecross-section by light is transformed into an asymmetric one. An interesting astrophysical phenomenon is that the shadow of a rotating black hole has the asymmetric bright side due to this property [43,44,45,46,47,48,49,50,51,52,53,54].…”

Light ring images of double photon spheres in black hole and wormhole space-times

“…In view of the discussion above, one of the main challenges of the community is to find black hole mimickers that, while being compatible with those tests that the Kerr solution passes (such as X-ray observations [31] and gravitational waves), it also allows for sufficiently large deviations from it to be distinguishable via observations [32]. However, many of the observationally viable models proposed so far amount to mild modifications in the shape and size of the light rings and/or the shadow that are hard to distinguish from the Kerr one [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] (for a review of analytical studies see [51]). Furthermore, it is extremely difficult to disentangle the degeneracy in the shadow's form between the background geometry, the modelling of the accretion flow, and the calibration parameters such as mass and angular momentum [52].…”