# Dark matter from scalar field fluctuations

## TL;DR

This paper explores how a massive scalar field during cosmic inflation can generate dark matter, predicting enhanced structure formation and providing a new mechanism for DM origin from early universe fluctuations.

## Contribution

It introduces a novel class of inflationary scenarios where scalar field fluctuations naturally produce dark matter, linking early universe dynamics to present-day structure formation.

## Key findings

- Scalar field fluctuations can source dark matter density during inflation.
- The scenarios predict an enhanced structure formation spectrum.
- The model allows testing dark matter interactions limited to gravity.

## Abstract

Dark matter (DM) may have its origin in a pre-Big Bang epoch, the cosmic inflation. Here, we consider for the first time a broad class of scenarios where a massive free scalar field unavoidably reaches an equilibrium between its classical and quantum dynamics in a characteristic time scale during inflation and sources the DM density. The study gives the abundance and perturbation spectrum of any DM component sourced by the scalar field. We show that this class of scenarios generically predicts enhanced structure formation, allowing one to test models where DM interacts with matter only gravitationally.