Abstract

Contributed Talk - Plenary

IMF Variations Across the DESI Galaxy Populations

Amara Mighty, Amélie Saintonge
University College London (UCL)

There exists an abundance of evidence that the initial mass function (IMF) is not the same in all galaxies and at all cosmic times, yet despite this, nearly all analyses continue to rely on the assumption of a constant IMF. Our work aims to form a cohesive picture of IMF variations across galaxy populations using the advantages offered by the DESI (Dark Energy Spectroscopic Instrument) dataset to systematically look for variations in the IMF as a function of galaxy properties and redshift. It is thought that local ISM conditions such as metallically and density influence the IMF, with these conditions fluctuating over the course of a galaxy’s evolution; resulting in systematic variations in the galaxy-integrated IMF across the galaxy population. The effects of these internal conditions can be assessed through measurable quantities such as star formation rate, metallicity, redshift, and more. With DESI, we improve sample size by a factor of 100 and access a larger parameter space compared to previous spectroscopic studies such as SDSS. This allows us to systematically quantify IMF variations over the redshift range 0 < z < 1, and over both the star-forming and quiescent galaxy population. We present the results of the first part of our analysis targeting star-forming galaxies 0 < z< 0.5 in the DESI Year 3 data release. We use Balmer line fluxes and optical colors to put constraints on the IMF slope through comparison with the galaxy spectral evolution models.