Initial Mass Function for Massive Galaxies at z$\sim$1

TL;DR

This study investigates the stellar Initial Mass Function normalization in massive early-type galaxies at redshift ~1, finding a Salpeter-like IMF and low dark matter fractions in their inner regions, using dynamical and stellar population models.

Contribution

It provides the first direct comparison of dynamical and stellar population M/L ratios for high-redshift massive galaxies, revealing IMF normalization and dark matter content.

Findings

Massive ETGs at z~1 have a Salpeter-like IMF.

Low dark matter fraction within inner regions of these galaxies.

Supports previous predictions of dark matter distribution at high redshift.

Abstract

We present the results on the stellar Initial Mass Function (IMF) normalisation of 68 massive ($M_\ast=10^{11}-10^{12}$$M_\odot$) Early-Type Galaxies (ETGs) at redshift of $\sim$1. This was achieved by deriving the stellar Mass-to-Light ratio (M/L) of the galaxies through axis-symmetric dynamical modelling and comparing it to the same derived via stellar population modelling through full spectrum fitting. The study also employs an Abundance Matching technique to account for the dark matter within the galaxies. The results demonstrate that massive ETGs at high redshifts on average have a Salpeter-like IMF normalisation, while providing observational evidence supporting previous predictions of low dark matter fraction in the inner regions ($\lesssim$ 1R$_{\rm e}$) of galaxies at higher redshift.