Structure formation with primordial black holes to alleviate early star formation tension revealed by JWST

TL;DR

This paper investigates how primordial black holes (PBHs) can explain the excess of high-redshift galaxies observed by JWST, by modifying the dark matter power spectrum and simulating galaxy formation.

Contribution

It introduces a model incorporating PBHs and a blue spectral index to match JWST galaxy observations, showing PBHs can alleviate early star formation tensions.

Findings

Increased high-redshift galaxy abundance in simulations with PBHs.

PBH-inclusive models reproduce JWST observations with realistic star formation efficiency.

PBHs could seed supermassive black holes of around 7.57 x 10^4 solar masses.

Abstract

This Letter explores the potential role of primordial black holes (PBHs) to address cosmological tensions as the presence of more massive than expected galaxies at high redshifts, as indicated by recent James Webb Space Telescope observations. Motivated by inflation models that enhance the power at scales beyond the observable range that produce PBHs with Schechter-like mass functions, we aim to explain the excess of high redshift galaxies via a modification of the $\Lambda$ cold dark matter power spectrum that consists in adding (i) a blue spectral index $n_b$ at $k_{\text{piv}}=10/$Mpc and (ii) Poisson and isocurvature contributions from massive PBHs that only make up $0.5\%$ of the dark matter.We simulated these models using the SWIFT code and find an increased abundance of high redshift galaxies in simulations that include PBHs. We compared these models to estimates from James Webb Space Telescope observations.Unlike the $\Lambda$ cold dark matter model, the inclusion of PBHs allowed us to reproduce the the observations with reasonable values for the star formation efficiency. Furthermore, the power spectra we adopted potentially produce PBHs that can serve as seeds for supermassive black holes with masses $7.57 \times 10^4 M_{\odot}$.