# Gravitational Instability of Exotic Compact Objects

## TL;DR

Exotic compact objects inspired by quantum gravity are generally gravitationally unstable and tend to collapse into black holes unless they violate energy conditions or have surfaces far from the horizon.

## Contribution

This paper demonstrates the gravitational instability of classical exotic compact objects due to accretion and gravitational waves, highlighting conditions needed to prevent collapse.

## Key findings

- Classical exotic objects are unstable under accretion and gravitational wave influence.
- Collapse to black holes is inevitable unless surfaces are far from the horizon or energy conditions are violated.
- Most exotic objects cannot remain stable without violating fundamental physical conditions.

## Abstract

Exotic compact objects with physical surfaces a Planckian distance away from where the horizon would have been are inspired in quantum gravity. Most of these objects are defined by a classical spacetime metric, such as boson stars, gravastars and wormholes. We show that these classical objects are gravitationally unstable because accretion of ordinary and dark matter, and gravitational waves forces them to collapse to a black hole by the Hoop conjecture. To avoid collapse, their surface must be a macroscopic distance away from the horizon or they must violate the null energy condition.