Gravitational lensing and shadows from thin-disks in Loop Quantum Gravity self-dual black holes

TL;DR

This paper investigates gravitational lensing and shadow images of Loop Quantum Gravity black holes with wormhole interiors, analyzing how their parameters affect observable phenomena compared to classical Schwarzschild black holes.

Contribution

It introduces a detailed analysis of lensing and shadow features of LQG black holes, incorporating observational constraints and accretion disk models, highlighting potential observable differences from classical black holes.

Findings

Parameter P constrained by EHT shadow size

Modifications in lensing observables compared to Schwarzschild

Black hole shadow and lensing signatures influenced by interior wormhole structure

Abstract

We analyze gravitational lensing and their cast images from thin-disks in shadow observations of a family of spherically symmetric black hole solutions previously derived within the framework of Loop Quantum Gravity. Such black holes depend on two parameters (besides the mass of the black hole itself), $P$ and $a_0$, the latter imbuing the configurations with an interior wormhole structure. Using the bounds from the Event Horizon Telescope regarding the shadow's radius of Sgr A$^*$ that constrain the parameter $P \lesssim 0.08(2\sigma)$ (at $a_0=0$), we study the modifications to weak and strong gravitational lensing induced by these geometries as compared to the Schwarzschild black hole within this range. In particular, we discuss several observables in the strong field regime related to the luminosity decay, the angular separation, and the flux ratio between multiples images of the source. Furthermore, we consider the cast images of these black holes when illuminated by a geometrically and optically thin accretion disk according to several semi-analytic profiles for the disk's emission.