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

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.