2020/12/12 by Thomas G. Bisbas, Jonathan C. Tan, Kei E. I. Tanaka +1 · 1 citation
Earth and Planetary Sciences · Physics and Astronomy · #Astrochemistry #Astrophysics #Astrophysics and Star Formation Studies #Atmospheric Ozone and Climate #Atomic carbon #Atomic physics #Cosmic ray #Galaxy #Hydrogen #Interstellar cloud #Interstellar medium #Ion #Ionization #Line (geometry) #Molecular cloud #Photodissociation #Physics #Range (aeronautics) #Stars #Stellar, planetary, and galactic studies #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.1093/mnras/stab121
33 pages, 24 figures, 3 tables. Submitted to MNRAS. Comments welcome!
arxiv created 2020/12/12 · openalex publication_date 2021/01/14 · arxiv updated 2021/01/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
ABSTRACT We present three-dimensional astrochemical simulations and synthetic observations of magnetized, turbulent, self-gravitating molecular clouds. We explore various galactic interstellar medium environments, including cosmic ray ionization rates in the range of ζCR = 10−17–10-14 \rm s-1, far-UV intensities in the range of G0 = 1–103 and metallicities in the range of Z = 0.1–2 \rm Z\odot . The simulations also probe a range of densities and levels of turbulence, including cases where the gas has undergone recent compression due to cloud–cloud collisions. We examine: (i) the column densities of carbon species across the cycle of C ii, C i, and CO, along with O i, in relation to the H i-to-H2 transition; (ii) the velocity-integrated emission of [C ii] 158 μm, [13C ii] 158 μm, [C i] 609 μm and 370 μm, [O i] 63 μm and 146 μm, and of the first ten 12CO rotational transitions; (iii) the corresponding Spectral Line Energy Distributions; (iv) the usage of [C ii] and [O i] 63 μm to describe the dynamical state of the clouds; (v) the behaviour of the most commonly used ratios between transitions of CO and [C i]; and (vi) the conversion factors for using CO and C i as H2-gas tracers. We find that enhanced cosmic ray energy densities enhance all aforementioned line intensities. At low metallicities, the emission of [C ii] is well connected with the H2 column, making it a promising new H2 tracer in metal-poor environments. The conversion factors of XCO and XC i depend on metallicity and the cosmic ray ionization rate, but not on FUV intensity. In the era of ALMA, SOFIA, and the forthcoming CCAT-prime telescope, our results can be used to understand better the behaviour of systems in a wide range of galactic and extragalactic environments.