# Testing Chern-Simons gravity with black holes?

## TL;DR

This paper assesses whether electromagnetic observations can differentiate Chern-Simons gravity black holes from Kerr black holes, finding the differences are too small for current detection capabilities.

## Contribution

The study develops simulations of electromagnetic signals around CS and Kerr black holes to evaluate observable differences, providing a quantitative comparison.

## Key findings

- Observable differences are around 0.1%, too small for current instruments.
- Current and near-future telescopes cannot distinguish CS from Kerr black holes.
- The results set constraints on testing CS gravity with electromagnetic observations.

## Abstract

We investigate the possibility to distinguish the small-coupling, slow-rotation black hole solution of Chern-Simons (CS) gravity from the Kerr solution. We develop simulations of electromagnetic observables in the vicinity of CS and Kerr black holes. We show that the typical relative observable difference between CS and Kerr spacetimes is of the order of 0.1% thus beyond reach of current or near-future instruments.