Carbon Monoxide Intensity Mapping at Moderate Redshifts

TL;DR

This paper evaluates the feasibility of using intensity mapping of the CO(1-0) line at redshift around 3, proposing new methods for power spectrum calculation and analyzing the potential for detection with hypothetical spectrographs.

Contribution

It introduces an alternative method for calculating the angular power spectrum for narrow bandwidth surveys and assesses the detectability of CO intensity fluctuations at moderate redshifts.

Findings

Three out of four models yield SNR > 10 within one year.

The alternative power spectrum calculation method is effective for small bandwidths.

Survey parameters significantly impact the detection prospects.

Abstract

We present a study of the feasibility of an intensity-mapping survey targeting the 115 GHz CO(1-0) rotational transition at $z\sim3$. We consider four possible models and estimate the spatial and angular power spectra of CO fluctuations predicted by each of them. The frequency bandwidths of most proposed CO intensity mapping spectrographs are too small to use the Limber approximation to calculate the angular power spectrum, so we present an alternative method for calculating the angular power spectrum. The models we consider span two orders of magnitude in signal amplitude, so there is a significant amount of uncertainty in the theoretical predictions of this signal. We then consider a parameterized set of hypothetical spectrographs designed to measure this power spectrum and predict the signal-to-noise ratios expected under these models. With the spectrographs we consider we find that three of the four models give an SNR greater than 10 within one year of observation. We also study the effects on SNR of varying the parameters of the survey in order to demonstrate the importance of carefully considering survey parameters when planning such an experiment.