Line intensity mapping: a "novel" window to the cosmic web

TL;DR

Line intensity mapping is a promising observational technique that captures the integrated emission from cosmic structures, including faint objects, to study galaxy evolution, large-scale structure, and fundamental physics in the universe.

Contribution

This paper provides an overview of line intensity mapping, reviewing its current status, key emission lines, modeling approaches, and potential scientific applications in the post-reionization universe.

Findings

Intensity mapping includes light from the faintest cosmic web objects.

The technique is promising with many upcoming experiments across the electromagnetic spectrum.

Systematic uncertainties and foreground contamination are acknowledged and addressed.

Abstract

Intensity mapping has been attracting increasing interest as a way to study galaxy evolution and the large scale structure of the Universe. Instead of detecting individual galaxies, we measure the integrated emission from a volume of the universe. Contrary to galaxy surveys, it includes light from the faintest objects in the cosmic web. We will start this overview by introducing line intensity mapping and review its current observational status. We will enumerate the most prominent emission lines for intensity mapping and discuss how to model their observed signal. The prospects of using this technique in the near future are very good with a wide range of experiments in different parts of the electromagnetic spectrum. As for any other observational tool, intensity mapping is not free of systematic uncertainties, some of which are intrinsic to it. We will briefly discuss them as well as the means to deal with foreground and background contamination. Here, we will focus on the science cases for intensity mapping in the post-reionization universe. These range from the history of star formation to measuring the acoustic scale and the fundamental physics.