# Predicting the intensity mapping signal for multi-$J$ CO lines

**Authors:** Natalie Mashian, Amiel Sternberg, Abraham Loeb  
**arXiv:** [1507.02686](https://arxiv.org/abs/1507.02686)  
**Date:** 2015-07-09  
**Summary page:** https://www.summarizepaper.com/en/paper/1507.02686v1/

## Key points

- Authors Natalie Mashian, Amiel Sternberg, and Abraham Loeb present a novel approach to estimating the intensity mapping signal of CO rotational lines during the Epoch of Reionization (EoR).
- Methodology based on large velocity gradient (LVG) modeling considers parameters such as gas kinetic temperature, volume density, velocity gradient, molecular abundance, and column density.
- Connection established between LVG parameters and global properties of host galaxies, focusing on star formation rate (SFR) and SFR surface density.
- Incorporation of empirically derived SFR-M relation for high redshift galaxies enables determination of specific intensity of CO rotational transitions as functions of host halo mass M and redshift z.
- Predictions indicate mean CO(1-0) brightness temperature ranging from approximately 1 μK at z = 6 to about 0.2 μK at z = 10 under certain assumptions about duty cycles for star formation and CO luminous activity.
- Higher rotational levels exhibit strong CO emission signals with average brightness temperatures around 0.3 μK and 0.1 μK for the CO J = 10->9 transition at redshifts z = 6 and z = 10 respectively.
- When duty cycles are set at unity, estimated CO(1-0) brightness temperature decreases to approximately 0.6 μK at z = 6 and around 0.03 μK at z =10.
- Reduction in signal strengths for higher J lines may decrease the likelihood of detecting these transitions with high significance in certain models proposed by the authors.
- Study provides valuable insights into predicting intensity mapping signals for multi-J CO lines during EoR by leveraging LVG modeling techniques and linking them to key galaxy properties like SFR and halo mass.

## Summary

In their paper titled "Predicting the intensity mapping signal for multi-$J$ CO lines," authors Natalie Mashian, Amiel Sternberg, and Abraham Loeb present a novel approach to estimating the intensity mapping signal of any CO rotational line emitted during the Epoch of Reionization (EoR). Their methodology is based on large velocity gradient (LVG) modeling, a radiative transfer technique that allows for the generation of the full CO spectral line energy distribution (SLED) by considering various parameters such as gas kinetic temperature, volume density, velocity gradient, molecular abundance, and column density. The authors establish a connection between these LVG parameters and the global properties of host galaxies, particularly focusing on star formation rate (SFR) and SFR surface density. By incorporating an empirically derived SFR-M relation for high redshift galaxies, they are able to express the LVG parameters and subsequently determine the specific intensity of any CO rotational transition as functions of host halo mass M and redshift z. Through integrating over a range of halo masses expected to host CO-luminous galaxies with M >= 10^8 M{_\odot}, the authors predict a mean CO(1-0) brightness temperature ranging from approximately 1 {\mu}K at z = 6 to about 0.2 {\mu}K at z = 10 under the assumption of duty cycles for star formation and CO luminous activity being 0.1 (f_{UV} = f_{duty} = 0.1). They note that in this model, higher rotational levels exhibit strong CO emission signals with average brightness temperatures around 0.3 {\mu}K and 0.1 {\mu}K for the CO J = 10->9 transition at redshifts z = 6 and z = 10 respectively. Furthermore, when considering duty cycles set at unity, the estimated CO(1-0) brightness temperature decreases to approximately 0.6 {\mu}K at z = 6 and around 0.03 {\mu}K at z =10. This reduction in signal strengths for higher J lines may decrease the likelihood of detecting these transitions with high significance in the f_{UV} = f_{duty} = 1 model proposed by the authors. Overall, this study provides valuable insights into predicting intensity mapping signals for multi-J CO lines during EoR by leveraging LVG modeling techniques and linking them to key galaxy properties like SFR and halo mass.