Emission Line Mapping of the Circumgalactic Medium of Nearby Galaxies

TL;DR

This paper discusses the potential of using emission line imaging to map the circumgalactic medium (CGM) of nearby galaxies, aiming to advance understanding of galaxy evolution and the galactic baryon cycle.

Contribution

It highlights the opportunity and upcoming efforts to image the CGM via recombination line emission, moving from statistical detections to detailed spectral-line images.

Findings

Recent statistical detection of CGM emission.

Potential to produce spectral-line images of individual galaxies.

Insights into the galactic baryon cycle expected in the next decade.

Abstract

The circumgalactic medium (CGM), which harbors > 50% of all the baryons in a galaxy, is both the reservoir of gas for subsequent star formation and the depository of chemically processed gas, energy, and angular momentum from feedback. As such, the CGM obviously plays a critical role in galaxy evolution. We discuss the opportunity to image this component using recombination line emission, beginning with the early results coming from recent statistical detection of this emission to the final goal of realizing spectral-line images of the CGM in individual nearby galaxies. Such work will happen in the next decade and provide new insights on the galactic baryon cycle.