Semi-Empirical Approach to [CII] Line Intensity Mapping

TL;DR

This paper introduces a semi-empirical, data-driven framework for modeling [CII] line intensity mapping, reducing uncertainties and enabling better predictions of large-scale structure evolution across cosmic history.

Contribution

It develops a minimal-parameter, observationally grounded model for galaxy line emissions, applicable to multiple spectral lines in intensity mapping studies.

Findings

Derived cosmic [CII] intensity over $0 \,\lesssim\, z \lesssim 10$

Assessed detectability with current and future facilities

Provided insights into large-scale structure and galaxy evolution

Abstract

The line intensity mapping technique involves measuring the cumulative emission from specific spectral lines emitted by galaxies and intergalactic gas. This method provides a way to study the matter distribution and the evolution of large-scale structures throughout the history of the Universe. However, modeling intensity mapping from ab-initio approaches can be challenging due to significant astrophysical uncertainties and noticeable degeneracies among astrophysical and cosmological parameters. To address these challenges, we develop a semi-empirical, data-driven framework for galaxy evolution, which features a minimal set of assumptions and parameters gauged on observations. By integrating this with stellar evolution and radiative transfer prescriptions for line emissions, we derive the cosmic [CII] intensity over an extended redshift range $0 \lesssim z \lesssim 10$. Our approach is quite general and can be easily applied to other key lines used in intensity mapping studies, such as [OIII] and the CO ladder. We then evaluate the detectability of the [CII] power spectra using current and forthcoming observational facilities. Our findings offer critical insights into the feasibility and potential contributions of intensity mapping for probing the large-scale structure of the Universe and understanding galaxy evolution.