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

Gert Hütsi, Martti Raidal, Juan Urrutia, Ville Vaskonen, Hardi Veermäe

Submitted on 4 November 2022, last revised on 14 November 2022


The James Webb Space Telescope has detected surprisingly luminous early galaxies that indicate a tension with the ΛCDM. 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 2×1018eV axions or if a fraction fPBH>0.005 of dark matter is composed of compact heavy 4×106M(fPBH/0.005)1 structures such as primordial black hole clusters. However, in both cases, the star formation efficiency needs to be significantly enhanced.


Comment: 6 pages, 4 figures; references added, discussion extended

Subjects: Astrophysics - Cosmology and Nongalactic Astrophysics; High Energy Physics - Phenomenology


The matter power spectrum for standard $\Lambda$CDM (black dashed) and for three values of $k_c$ with $n=0$ (solid) and $n=1$ (dashed). The points with errors correspond to SDSS measurements of galaxy clustering from luminous red galaxies (purple)~\cite{Reid:2009xm} and Lyman-$\alpha$ forest (black)~\cite{Chabanier:2019eai} and HST measurements of UV luminosity function (blue)~\cite{Sabti:2021unj}. The blue dashed curve shows the maximal cut-off scale for $k^4$ growth of the adiabatic curvature power spectrum from COBE/Firas bound on $\mu$ and $y$ distortions~\cite{Chluba:2013dna}.