SPICA and the Chemical Evolution of Galaxies: The Rise of Metals and Dust

TL;DR

This paper discusses how the SPICA infrared observatory can probe dust-obscured star formation and chemical evolution in galaxies from redshift 1 to 3 by analyzing spectral lines and dust features in the mid- to far-IR range.

Contribution

It explores the potential of SPICA observations to understand galaxy chemical evolution, metal assembly, and dust composition at high redshifts, filling observational gaps.

Findings

SPICA can access key spectral lines in dust-obscured galaxies at high redshift.

Infrared spectral features serve as robust tracers of heavy element abundances.

SPICA's capabilities complement other facilities for studying galaxy evolution.

Abstract

The physical processes driving the chemical evolution of galaxies in the last $\sim 11\, \rm{Gyr}$ cannot be understood without directly probing the dust-obscured phase of star-forming galaxies and active galactic nuclei. This phase, hidden to optical tracers, represents the bulk of star formation and black hole accretion activity in galaxies at $1 < z < 3$. Spectroscopic observations with a cryogenic infrared (IR) observatory like SPICA will be sensitive enough to peer through the dust-obscured regions of galaxies and access the rest-frame mid- to far-IR range in galaxies at high-$z$. This wavelength range contains a unique suite of spectral lines and dust features that serve as proxies for the abundances of heavy elements and the dust composition, providing tracers with a feeble response to both extinction and temperature. In this work, we investigate how SPICA observations could be exploited to understand key aspects in the chemical evolution of galaxies: the assembly of nearby galaxies based on the spatial distribution of heavy element abundances, the global content of metals in galaxies reaching the knee of the luminosity function up to $z \sim 3$, and the dust composition of galaxies at high-$z$. Possible synergies with facilities available in the late 2020s are also discussed.