"The AGEL Survey Unveils an Overabundance of Low-Mass Stars 9 Gyr Ago"

Abstract:

The first billion years of cosmic history set the stage for the galaxies we observe today, yet key uncertainties remain in how the earliest stellar populations shaped galaxy evolution across time. A critical missing piece is the stellar initial mass function (IMF), which governs star formation and impacts derived galaxy properties — from stellar masses to chemical enrichments. While nearby massive galaxies show evidence for "bottom-heavy" IMFs, indicating an excess of low-mass stars, we do not yet know when or how this bottom-heavy IMF emerged. I’ll present results from the an analysis of the low-mass initial mass function at z=1, thanks to JWST/NIRSpec IFU observations of two gravitationally lensed, massive quiescent galaxies which point to an already bottom heavy IMF 9 Gyr ago.

This analysis is part of the The ASTRO 3D Galaxy Evolution with Lenses (AGEL) Survey- an ongoing effort to spectroscopically confirm a diverse sample of gravitational lenses with high spatial resolution imaging, to facilitate a broad range of science outcomes. The AGEL systems span single galaxy-scale deflectors to groups and clusters, and include rare targets such as galaxy-scale lenses with multiple sources, lensed quiescent galaxies, and Einstein rings. I will also give a brief overview of the survey and highlight the publicly available data products.