Warm molecular Hydrogen at high redshift with the James Webb Space Telescope

TL;DR

This paper discusses how the James Webb Space Telescope will observe warm molecular hydrogen in high-redshift galaxies, shedding light on galaxy formation, cooling processes, and feedback mechanisms through H$_2$ emission lines.

Contribution

It highlights the importance of H$_2$ emission as a cooling agent in turbulent, high-redshift galaxies and prepares for JWST observations to explore galaxy assembly.

Findings

H$_2$ lines indicate turbulent dissipation in galaxies.

Strong H$_2$ emission correlates with galaxy turbulence.

JWST will enable detailed study of H$_2$ cooling in early galaxies.

Abstract

The build-up of galaxies is regulated by a complex interplay between gravitational collapse, galaxy merging and feedback related to AGN and star formation. The energy released by these processes has to dissipate for gas to cool, condense, and form stars. How gas cools is thus a key to understand galaxy formation. \textit{Spitzer Space Telescope} infrared spectroscopy revealed a population of galaxies with weak star formation and unusually powerful H$_2$ line emission. This is a signature of turbulent dissipation, sustained by large-scale mechanical energy injection. The cooling of the multiphase interstellar medium is associated with emission in the H$_2$ lines. These results have profound consequences on our understanding of regulation of star formation, feedback and energetics of galaxy formation in general. The fact that H$_2$ lines can be strongly enhanced in high-redshift turbulent galaxies will be of great importance for the \textit{James Webb Space Telescope} observations which will unveil the role that H$_2$ plays as a cooling agent in the era of galaxy assembly.