Origin of discrepancies between observed and simulated high-redshift LAE populations

Establish whether the discrepancies between the observed LAEs and the SPHINX20 simulated galaxies arise from limitations of the simulations, observational selection effects, or genuine differences between the simulated and observed high-redshift galaxy populations, using JWST observations spanning a broader range of galaxy properties.

Background

The paper compares a sample of observed Lyman-alpha emitters with galaxies from the SPHINX20 radiation-hydrodynamics simulations. Although the two samples occupy similar stellar-mass and Ly-alpha-equivalent-width regimes, they differ in their nebular emission-line distributions and mass–metallicity relations. In particular, the simulations occupy a narrower locus in the BPT diagram and predict a steeper mass–metallicity relation than the observationally inferred relation.

Several explanations remain possible: the simulations may inadequately model stellar populations, chemical enrichment, stellar feedback, or the unresolved multiphase interstellar medium; the observations may be affected by selection effects and substantial metallicity uncertainties; or the discrepancies may represent genuine physical differences between simulated and observed high-redshift LAE populations. The authors identify broader JWST spectroscopic samples covering a wider range of galaxy properties as necessary to distinguish among these possibilities.

References

Future JWST observations spanning a broader range of galaxy properties will be essential for establishing whether these differences reflect limitations of the simulations, observational selection effects, or genuine differences between the simulated and observed high-redshift galaxy populations.

— Are High-EW LAEs good analogs for the earliest galaxies? A study on the ionizing conditions and gas properties of LAEs at $2\lesssim z\lesssim7  (2610.21232 - Pless et al., 15 Oct 2026) in Section 4.2, “Comparison to Simulations”