Collapsing objects with the same gravitational trajectory can radiate away different amount of energy

TL;DR

This paper demonstrates that two collapsing objects with identical gravitational trajectories can emit different amounts of radiation depending on their composition, revealing potential information about their internal properties.

Contribution

It shows that objects with the same mass, charge, and angular momentum can radiate differently based on their material properties, impacting the understanding of information release during collapse.

Findings

Different radiation amounts for shells with same trajectory and different compositions

Implications for reconstructing initial object properties from radiation

Potential insights into the black hole information paradox

Abstract

We study radiation emitted during the gravitational collapse from two different types of shells. We assume that one shell is made of dark matter and is completely transparent to the test scalar (for simplicity) field which belongs to the standard model, while the other shell is made of the standard model particles and is totally reflecting to the scalar field. These two shells have exactly the same mass, charge and angular momentum (though we set the charge and angular momentum to zero), and therefore follow the same geodesic trajectory. However, we demonstrate that they radiate away different amount of energy during the collapse. This difference can in principle be used by an asymptotic observer to reconstruct the physical properties of the initial collapsing object other than mass, charge and angular momentum. This result has implications for the information paradox and expands the list of the type of information which can be released from a collapsing object.