Two descriptions of dark matter around a black hole: photon sphere, shadow, and lensing

TL;DR

This paper compares two models of dark matter around black holes, analyzing their photon spheres, shadows, and lensing effects, revealing contrasting behaviors and distinctive lensing phenomena.

Contribution

It introduces a detailed comparison of vacuum and Einstein cluster dark matter models around black holes, highlighting their different observational signatures.

Findings

Einstein cluster causes larger shadow deviations than Schwarzschild.

Distinct lensing phenomena are identified in both models.

Contrasting photon sphere behaviors are observed.

Abstract

We examine the observational discrepancies of two widely used models describing anisotropic (dark) matter distributions around a black hole, focusing on their photon spheres, shadow radii, and lensing observables. The models considered are the vacuum and Einstein cluster dark matter models, characterized by negative and zero radial pressure, respectively. The analysis reveals that these models display contrasting photon sphere behaviors. In particular, the Einstein cluster results in a more pronounced deviation in the shadow radius relative to the standard Schwarzschild black hole. Additionally, a distinctive lensing phenomenon associated with the matter halo is identified in both models.