# A lower bound on dark matter mass

**Authors:** Mustafa A. Amin, Mehrdad Mirbabayi  
**arXiv:** [2211.09775](https://arxiv.org/abs/2211.09775)  
**Date:** 2022-11-17  
**Summary page:** https://www.summarizepaper.com/en/paper/2211.09775v2/

## Key points

- Mustafa A. Amin and Mehrdad Mirbabayi propose a lower bound on the mass of dark matter particles to be around $10^{-19}$ eV.
- The argument is based on observed phenomena such as the non-detection of free-streaming suppression and white-noise enhancement of density perturbations.
- Dark matter plays a crucial role in understanding the universe, impacting astrophysical and cosmological scales.
- Many aspects of dark matter remain unknown, including its particle's mass or spin and any non-gravitational interactions they may have.
- Amin and Mirbabayi introduce two key effects to establish their lower bound argument: excess white noise power and suppression of power due to free-steaming.
- These effects serve as relatively model-independent constraints on the microscopic properties of dark matter particles.

## Summary

In their paper, Mustafa A. Amin and Mehrdad Mirbabayi argue for a lower bound on the mass of dark matter particles. They propose this bound to be around $10^{-19}$ eV under the assumption that dark matter is produced after inflation through a process characterized by a finite correlation length. The authors base their argument on observed phenomena such as the non-detection of free-streaming suppression and the white-noise enhancement of density perturbations. Dark matter plays a crucial role in our understanding of the universe, impacting astrophysical scales like dwarf galaxies and cosmological scales such as the Cosmic Microwave Background (CMB). However, many aspects of dark matter remain unknown, including its particle's mass or spin and any non-gravitational interactions they may have. Additionally, there is no consensus on how dark matter was formed in the early universe. By analyzing current observations that support an approximately scale-invariant initial power spectrum of dark matter density fluctuations for comoving wavenumbers below a certain threshold, Amin and Mirbabayi introduce two key effects to establish their lower bound argument: excess white noise power and suppression of power due to free-steaming. These effects serve as relatively model-independent constraints on the microscopic properties of dark matter particles. Overall, this study provides valuable insights into the nature of dark matter by proposing a conservative lower bound on its mass based on observational data and theoretical considerations related to its formation and characteristics in the post-inflationary universe.