Black Hole Shadows in M-theory Scenarios

TL;DR

This paper explores how M-theory inspired models influence black hole shadows, revealing how M2-branes affect shadow size and shape, and connecting theoretical predictions with observational data from the Event Horizon Telescope.

Contribution

It provides a detailed analysis of black hole shadow geometries in M-theory scenarios, including effects of M2-branes and rotation, and links these to observational constraints.

Findings

M2-brane number controls shadow size

Rotation causes cardioid-shaped shadow distortions

Energy emission rate peak decreases with M2-brane number

Abstract

We study the shadows of four dimensional black holes in M-theory inspired models. We first inspect the influence of M2-branes on such optical aspects for non-rotating solutions. In particular, we show that the M2-brane number can control the circular shadow size. This geometrical behavior is distorted for rotating solutions exhibiting cardioid shapes in certain moduli space regions. Implementing a rotation parameter, we analyze the geometrical shadow deformations. Among others, we recover the circular behaviors for a large M2-brane number. Investigating the energy emission rate at high energies, we find, in a well-defined approximation, that the associated peak decreases with the M2-brane number. Moreover, we investigate a possible connection with observations (from Event Horizon Telescope or future devices) from a particular M-theory compactification by deriving certain constraints on the M2-brane number in the light of the $M87^\star$ observational parameters.