# Structure Formation and Exotic Compact Objects in a Dissipative Dark Sector

## TL;DR

This paper explores the formation of complex structures and exotic compact objects in a simple dissipative dark-sector model, revealing potential observable signatures that inform dark matter particle properties.

## Contribution

It provides a comprehensive analysis of structure formation in a minimal dark-sector model, including the formation of dark galaxies, stars, and black holes, without requiring interactions with visible matter.

## Key findings

- Dark-electron halos fragment into a range of clumps from solar to galaxy masses.
- Dark stars and black holes can form within the Milky Way from dark-electron collapse.
- Exotic dark objects may be detectable with future high-precision astronomical observatories.

## Abstract

We present the complete history of structure formation in a simple dissipative dark-sector model. The model has only two particles: a dark electron, which is a subdominant component of dark matter, and a dark photon. Dark-electron perturbations grow from primordial overdensities, become non-linear, and form dense dark galaxies. Bremsstrahlung cooling leads to fragmentation of the dark-electron halos into clumps that vary in size from a few to millions of solar masses, depending on the particle model parameters. In particular, we show that asymmetric dark stars and black holes form within the Milky Way from the collapse of dark electrons. These exotic compact objects may be detected and their properties measured at new high-precision astronomical observatories, giving insight into the particle nature of the dark sector without the requirement of non-gravitational interactions with the visible sector.