# On estimation of contamination from hydrogen cyanide in carbon monoxide line intensity mapping

## TL;DR

This paper investigates the potential contamination of CO line intensity mapping surveys by HCN emission, finding that under typical models, the impact on CO measurements is minimal, less than 1%.

## Contribution

It introduces an empirical model to estimate HCN contamination effects on CO intensity mapping, highlighting the conditions under which contamination is negligible.

## Key findings

- HCN contamination effects are very small for the fiducial model
- Bias in CO detection significance due to HCN is less than 1%
- Model assumptions significantly influence contamination estimates

## Abstract

Line-intensity mapping surveys probe large-scale structure through spatial variations in molecular line emission from a population of unresolved cosmological sources. Future such surveys of carbon monoxide line emission, specifically the CO(1-0) line, face potential contamination from a disjoint population of sources emitting in a hydrogen cyanide emission line, HCN(1-0). This paper explores the potential range of the strength of HCN emission and its effect on the CO auto power spectrum, using simulations with an empirical model of the CO/HCN--halo connection. We find that effects on the observed CO power spectrum depend on modeling assumptions but are very small for our fiducial model based on our understanding of the galaxy--halo connection, with the bias in overall CO detection significance due to HCN expected to be less than 1%.