2024/09/06 by Ryan P. Keenan, Daniel P. Marrone, Keenan, Ryan P. +3 · 3 citations
Chemistry · Earth and Planetary Sciences · Environmental Science · #Astrophysics of Galaxies (astro-ph.GA) #Atmospheric Ozone and Climate #Atmospheric and Environmental Gas Dynamics #FOS: Physical sciences #Spectroscopy and Laser Applications
paper · pdf · doi:10.48550/arxiv.2409.03963
openalex publication_date 2024/09/06 · openalex created_date 2024/10/21 · openalex updated_date 2026/07/28
The CO(1-0) line has been carefully calibrated as a tracer of molecular gas mass. However, recent studies often favor higher J CO transitions which are brighter and accessible for redshift ranges where CO(1-0) is not. These lines are not perfect analogues for CO(1-0), owing to their more stringent excitation conditions, and must be calibrated for use as molecular gas tracers. Conversely, observations of multiple CO lines in a single target can constrain additional gas properties beyond mass. I will present the Arizona Molecular ISM Survey with the SMT (AMISS), a multi-CO line survey of z<0.05 galaxies conducted with the CO(1-0), CO(2-1) and CO(3-2) lines. The project targeted a representative sample of 109 Msun < M* < 1011.5 Msun galaxies. The final survey includes CO(2-1) spectra of 176 galaxies and CO(3-2) spectra for a subset of 45 supplemented by new and archival CO(1-0) spectra for all targets. I will present the results of our study of CO luminosity ratios, showing that CO(2-1) and CO(3-2) are systematically fainter relative to CO(1-0) in galaxies with less star formation activity. These results provide a reference for comparison to ongoing high-redshift gas excitation studies with ALMA, as well as a tool for converting between CO lines in studies of nearby galaxies.