Universität zu Köln

Bisbas, Thomas G., Tan, Jonathan C. and Tanaka, Kei E., I (2021). Photodissociation region diagnostics across galactic environments. Mon. Not. Roy. Astron. Soc., 502 (2). S. 2701 - 2733. OXFORD: OXFORD UNIV PRESS. ISSN 1365-2966

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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 zeta(CR) = 10(-17)-10(-14)S(-1), far-UV intensities in the range of G(theta) = 1-10(3) and metallicities in the range of Z = 0.1-2Z(circle dot). 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 CII, CI, and CO, along with OI, in relation to the H I-to-H-2 transition; (ii) the velocity-integrated emission of [CII] 158 mu m, [C-13 II] 158 mu m, [C I] 609 mu m and 370 mu m, [O I] 63 mu m and 146 mu m, and of the first ten (CO)-C-12 rotational transitions; (iii) the corresponding Spectral Line Energy Distributions; (iv) the usage of [C II] and [O I] 63 mu m to describe the dynamical state of the clouds; (v) the behaviour of the most commonly used ratios between transitions of CO and [CI]; and (vi) the conversion factors for using CO and CI as H-2-gas tracers. We find that enhanced cosmic ray energy densities enhance all aforementioned line intensities. At low metallicities, the emission of [C11] is well connected with the H-2 column, making it a promising new H-2 tracer in metal-poor environments. The conversion factors of X-CO and X-CI 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.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Bisbas, Thomas G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Tan, Jonathan C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Tanaka, Kei E., I UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-594536
DOI:	10.1093/mnras/stab121
Journal or Publication Title:	Mon. Not. Roy. Astron. Soc.
Volume:	502
Number:	2
Page Range:	S. 2701 - 2733
Date:	2021
Publisher:	OXFORD UNIV PRESS
Place of Publication:	OXFORD
ISSN:	1365-2966
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language POLYCYCLIC AROMATIC-HYDROCARBONS; CO-TO-H-2 CONVERSION FACTOR; LOCAL INTERSTELLAR-MEDIUM; C-12/C-13 ISOTOPE RATIO; NEUTRAL ATOMIC CARBON; STAR-FORMING GALAXIES; MOLECULAR CLOUDS; FINE-STRUCTURE; COSMIC-RAYS; GMC COLLISIONS Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/59453