2024/09/04 by F. P. Israël, R. Güsten, Israel, F. P. +3
Chemistry · Environmental Science · Physics and Astronomy · #Astrophysics and Star Formation Studies #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Impact of Light on Environment and Health #Spectroscopy and Laser Applications
paper · pdf · doi:10.48550/arxiv.2409.02987
openalex publication_date 2024/09/04 · openalex created_date 2024/10/19 · openalex updated_date 2026/07/28
We summarize all available 13CO and accompanying 12CO measurements of local galaxy centers in transitions of J=5-4 and higher, including new APEX 13CO(6-5) and 12CO(6-5) observations of 11 galaxies. The observed integrated temperature ratios of 12CO(6-5) to 12CO(1-0) range from 0.10 to 0.45. Multi-aperture data indicate that 13CO(6-5) is more centrally concentrated than 12CO(6-5). The emission of 12CO(6-5) and HCO+ but not HCN may be correlated. The new data are essential to constrain the physical properties of the galaxy center molecular gas even in a simple two-phase model approximating the more complex multi-phase structure. In all galaxies, except the Seyfert AGN galaxy NGC 1068, high J emission from the center is dominated by a dense (n = 100 000) and relatively cool (T = 20 to 60 K) high-pressure gas. In contrast, the low-J lines are dominated in most galaxies by low-pressure gas of a moderate density (n = 1000) and more elevated temperature (T = 60 to 150 K). The three exceptions with significant high-pressure gas contributions to the low J emission are all associated with active central star formation.