2024/09/02 by Charlotte Simmonds, Simmonds, C., Sandro Tacchella +55 · 8 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics of Galaxies (astro-ph.GA) #Cosmology and Gravitation Theories #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena
paper · pdf · doi:10.48550/arxiv.2409.01286
openalex publication_date 2024/09/02 · openalex created_date 2024/09/29 · openalex updated_date 2026/07/28
We use NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) to study the ionising properties of a sample of 15721 galaxies at 3 ≤ z_\rmphot ≤ 9, 90% complete in stellar mass down to log(M⋆/[M\odot])≈ 7.5. Out of the full sample, 1620 of the galaxies have spectroscopic redshift measurements from the literature. We use the spectral energy distribution fitting code Prospector to fit all available photometry and infer galaxy properties. We find a significantly milder evolution of the ionising photon production efficiency (\xion\/) with redshift and UV magnitude than previously reported. Interestingly, we observe two distinct populations in \xion\/, distinguished by their burstiness (given by SFR10/SFR100). Both populations show the same evolution with z and M_\rmUV, but have a different \xion\/ normalisation. We convolve the more representative log(ξ_\rmion (z,M_\rmUV)) relations (accounting for ∼96% of the sample), with luminosity functions from literature, to place constraints on the cosmic ionising photon budget. By combining our results, we find that one of our models can match the observational constraints from the \lya\/ forest at z\lesssim6. We conclude that galaxies with M_\rmUV between -16 and -20, adopting a reasonable escape fraction, can produce enough ionising photons to ionise the Universe, without exceeding the required ionising photon budget.