The molecular diversity of the ISM in galaxies across cosmic time

TL;DR

This paper discusses the importance of submillimetre molecular line observations for understanding the physical and chemical processes in galaxy evolution, emphasizing the need for comprehensive surveys across cosmic time.

Contribution

It highlights the current limitations in molecular inventories of galaxies and advocates for future multi-species, multi-transition surveys to better understand ISM processes from the early universe to today.

Findings

Current molecular inventories are limited to a few extreme galaxies.

Future surveys will enable detailed chemical diagnostics of galaxy evolution.

Extragalactic astrochemistry offers insights into gas response and galaxy growth.

Abstract

Submillimetre molecular lines (e.g., CO, HCN, SiO) provide a uniquely powerful view of the physical and chemical processes that govern star formation (SF) and galaxy evolution. Yet, our current picture of the molecular universe beyond the Milky Way remains strikingly incomplete: broad chemical inventories exist for only a handful of galaxies, typically more extreme than the Milky Way, constrained by sensitivity limits and narrow survey strategies. In the 2040s, surveying galaxies with multi-species, multi-transitions observations across diverse galactic environments will be crucial to establish effective chemical diagnostics of the various ISM processes from the early universe to $z=0$. Extragalactic astrochemistry provides a uniquely sensitive probe of the physical processes shaping galaxies, allowing us to understand, species by species, how gas responds to its local environment and how galaxies grow, transform, and recycle matter over cosmic time.