# New scalar compact objects in Ricci-based gravity theories

## TL;DR

This paper develops a method to generate new scalar field solutions in Ricci-based gravity theories, revealing exotic compact objects like wormholes and black hole mimickers that differ from traditional GR solutions.

## Contribution

It introduces a mapping technique to derive exact scalar solutions in Ricci-based gravities from GR solutions, uncovering novel compact objects without horizons.

## Key findings

- Discovered solutions include wormholes, shells, and horizonless compact objects.
- Identified objects that mimic black holes but lack horizons.
- Revealed new types of scalar compact objects with unique topologies.

## Abstract

Taking advantage of a previously developed method, which allows to map solutions of General Relativity into a broad family of theories of gravity based on the Ricci tensor (Ricci-based gravities), we find new exact analytical scalar field solutions by mapping the free-field static, spherically symmetric solution of General Relativity (GR) into quadratic $f(R)$ gravity and the Eddington-inspired Born-Infeld gravity. The obtained solutions have some distinctive feature below the would-be Schwarzschild radius of a configuration with the same mass, though in this case no horizon is present. The compact objects found include wormholes, compact balls, shells of energy with no interior, and a new kind of object which acts as a kind of wormhole membrane. The latter object has Euclidean topology but connects antipodal points of its surface by transferring particles and null rays across its interior in virtually zero affine time. We point out the relevance of these results regarding the existence of compact scalar field objects beyond General Relativity that may effectively act as black hole mimickers.