Starlight from JWST: Implications for star formation and dark matter models

¹ Keemilise ja Bioloogilise Füüsika Instituut, Rävala pst. 10, 10143 Tallinn, Estonia
² Department of Cybernetics, Tallinn University of Technology, Akadeemia tee 21, 12618 Tallinn, Estonia
³ King’s College London, Strand, London, WC2R 2LS United Kingdom
⁴ Theoretical Physics Department, CERN, Geneva, Switzerland
⁵ Dipartimento di Fisica e Astronomia, Università degli Studi di Padova, Via Marzolo 8, 35131 Padova, Italy
⁶ Istituto Nazionale di Fisica Nucleare, Sezione di Padova, Via Marzolo 8, 35131 Padova, Italy

^⋆ Corresponding author: juan.urrutia@kbfi.ee

Received: 5 May 2025
Accepted: 12 August 2025

Abstract

We compared the star formation rate in different dark matter (DM) models with UV luminosity data from JWST up to z ≃ 25 and legacy data from HST. We find that a transition from a Salpeter population to top-heavy Pop III stars is likely at z ≃ 10, and that beyond z = 10 − 15 the feedback from supernovae and active galactic nuclei is progressively reduced, so that at z ≃ 25 the production of stars is almost free from any feedback. We compared fuzzy and warm DM models that suppress small-scale structures with the CDM paradigm, and find that the fuzzy DM mass > 5.6 × 10⁻²² eV and the warm DM mass > 1.5 keV at a 95% CL. The fits of the star formation rate parametrisation do not depend strongly on the DM properties within the allowed range. We find no preference over CDM for enhanced matter perturbations associated with axion mini-clusters or primordial black holes. The scale of the enhancement of the power spectrum should be > 25 Mpc⁻¹ at the 95% CL, excluding axion mini-clusters produced for m_a < 6.6 × 10⁻¹⁷ eV or heavy primordial black holes that constitute a fraction f_PBH > max[105 M_⊙/m_PBH, 10⁻⁴(m_PBH/10⁴ M_⊙)^−0.09] of DM.