Identifying Variations to the IMF at High-$z$ Through Deep Radio Surveys

TL;DR

Deep radio surveys at high redshifts can help identify variations in the stellar initial mass function by isolating thermal emission, especially when combined with ALMA and JWST data, offering insights into early galaxy star formation.

Contribution

This paper proposes a novel method using deep radio continuum observations at frequencies above 10 GHz to detect IMF variations in high-redshift galaxies, leveraging upcoming telescope capabilities.

Findings

Thermal radio emission becomes dominant at high z due to suppressed non-thermal emission.

Combining radio, ALMA, and JWST data enhances the detection of IMF variations.

Next-generation facilities will improve measurements of star formation rates in early galaxies.

Abstract

In this article I briefly describe how deep radio surveys may provide a means to identify variations in the upper end of the initial mass function (IMF) in star-forming galaxies at high redshifts (i.e., $z\gtrsim$3). At such high redshifts, I argue that deep radio continuum observations at frequencies $\gtrsim$10 GHz using next generation facilities (e.g., EVLA, MeerKAT, SKA/NAA) will likely provide the most accurate measurements for the ionizing photon rates (star formation rates; SFRs) of normal galaxies since their non-thermal emission should be highly suppressed due to the increased inverse Compton (IC) losses from the cosmic microwave background (CMB), leaving only thermal (free-free) emission detectable. Thus, a careful analysis of such observations in combination with future ALMA and JWST data, measuring the rest-frame far-infrared and UV emission from the same population of galaxies, may yield the best means to search for variability in the stellar IMF at such epochs.