Did JWST observe imprints of axion miniclusters or primordial black holes?

TL;DR

This paper explores whether features like axion miniclusters or primordial black holes could explain early galaxy luminosity observations from JWST, suggesting specific dark matter compositions and the need for increased star formation efficiency.

Contribution

It introduces models with modified matter power spectra to account for JWST observations, proposing axion miniclusters or primordial black holes as potential explanations.

Findings

Axion masses around 2×10^{-18} eV could resolve the tension.

A fraction greater than 0.005 of dark matter as primordial black holes could explain observations.

Enhanced star formation efficiency is required in both scenarios.

Abstract

The James Webb Space Telescope has detected surprisingly luminous early galaxies that indicate a tension with the $\Lambda$CDM. Motivated by scenarios including axion miniclusters or primordial black holes, we consider power-law modifications of the matter power spectrum. We show that the tension could be resolved if dark matter consists of $2\times 10^{-18}{\rm eV}$ axions or if a fraction $f_{\rm PBH} > 0.005$ of dark matter is composed of compact heavy $4\times 10^6 M_\odot (f_{\rm PBH}/0.005)^{-1}$ structures such as primordial black hole clusters. However, in both cases, the star formation efficiency needs to be significantly enhanced.