# Evolution of black hole shadow in the presence of ultralight bosons

## TL;DR

This paper investigates how ultralight bosons can influence black hole shadows through superradiance, potentially allowing detection of such particles by observing changes in the shadow's size with improved measurement sensitivity.

## Contribution

It provides a detailed analysis of black hole shadow evolution due to ultralight bosons, offering estimates on the time scales and observational signatures for SgrA*.

## Key findings

- Shadow size increase is possible within certain parameter ranges.
- Detection requires measurement sensitivity improvement from 25 μas to 0.1 μas.
- Potential to constrain ultralight boson properties through shadow observations.

## Abstract

Kerr black holes coupled to quantized bosonic fields display a special version of the Hawking effect, governed by the superradiance condition. This leads to rapid growth of boson cloud through spontaneous creation, leading to slowing down of the black hole, and detectable as growth of the black hole shadow. This can be developed into a technique for searching or constraining the existence of ultralight bosons. We study this phenomenon for spin-0 bosons in the shadow of a black hole, with a detailed analysis of Sgr$A^*$, and put estimates on the evolution time scales and subsequent change in the black hole shadow features. Our study shows that there is a small window of parameters where the increase of shadow of a supermassive black hole may be visible, but only if the sensitivity of measurements increases from current 25 $\mu$as to about 0.1 $\mu$as.