# Upper bound on the GUP parameter using the black hole shadow

## TL;DR

This paper derives an upper limit on the GUP parameter based on black hole shadow observations, linking shadow shape deviations to quantum gravity effects, and applies recent M87* data to constrain the parameter.

## Contribution

It introduces a novel method to constrain the GUP parameter using black hole shadow deviations and recent observational data.

## Key findings

- GUP parameter constrained to ^{90} from M87* shadow data
- Relation established between GUP parameter and shadow deviation from circularity
- Provides a new observational bound on quantum gravity effects

## Abstract

An upper bound on the parameter that provides a generalized uncertainty principle (GUP) is obtained from the black hole shadow. With the aid of a recent constraint between regular black holes and the GUP parameter, it is indicated a relation between this parameter and the deviation from circularity of the black hole shadow. In the case of the recent announcement of the M87* results from the Event Horizon Telescope collaboration, a deviation from circularity $\lesssim 10\%$ imposes a GUP parameter $\beta_0 <10^{90}$.