Low-Metallicity Model Predicts 10x Higher SLSN Rates at z>2 Than SFR-Tracing Assumptions

The paper introduces a redshift- and metallicity-dependent rate framework that folds in galaxy stellar-mass functions, O/H and Fe/H scaling relations, and efficiency curves calibrated to local SLSN hosts. Applied to core-collapse progenitors, it yields rates that diverge sharply from pure star-formation history models beyond z=2 because low-metallicity galaxies remain more abundant than previously assumed in simple extrapolations.

This matters for cosmology because SLSNe are proposed as high-redshift standard candles; an order-of-magnitude rate increase changes both detection forecasts and the expected contamination in deep time-domain surveys. It also aligns with earlier observational hints from DES and PS1 that SLSN host metallicities skew lower than the field at fixed stellar mass.

The main limitation is reliance on local metallicity-efficiency scalings extrapolated to z>3 without direct high-redshift calibration. Stronger evidence would come from a magnitude-limited sample of z>2 SLSNe with host spectroscopy from JWST or ELT, testing whether the predicted rate upturn materializes.

Future surveys can now prioritize metal-poor galaxy fields and adjust cadence strategies to capture the enhanced high-z population the model forecasts.