Populating H2 and CO in galaxy simulation with dust evolution

Abstract There are two major theoretical issues for the star formation law (the relation between the surface densities of molecular gas and star formation rate on a galaxy scale): (i) At low metallicity, it is not obvious that star-forming regions are rich in H2 because the H2 formation rate depends...

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Published in:Monthly notices of the Royal Astronomical Society 2018-02, Vol.474 (2), p.1545-1563
Main Authors: Chen, Li-Hsin, Hirashita, Hiroyuki, Hou, Kuan-Chou, Aoyama, Shohei, Shimizu, Ikkoh, Nagamine, Kentaro
Format: Article
Language:English
Subjects:
Astrochemistry
Computer simulation
Cosmic dust
Disk galaxies
Dust
Galactic evolution
Galaxies
Grain size
Grain size distribution
Interstellar matter
Metallicity
Metals
Molecular gases
Particle size
Post-production processing
Radiation
Spatial resolution
Star & galaxy formation
Star formation rate
Stellar evolution
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Summary:Abstract There are two major theoretical issues for the star formation law (the relation between the surface densities of molecular gas and star formation rate on a galaxy scale): (i) At low metallicity, it is not obvious that star-forming regions are rich in H2 because the H2 formation rate depends on the dust abundance; and (ii) whether or not CO really traces H2 is uncertain, especially at low metallicity. To clarify these issues, we use a hydrodynamic simulation of an isolated disc galaxy with a spatial resolution of a few tens parsecs. The evolution of dust abundance and grain size distribution is treated consistently with the metal enrichment and the physical state of the interstellar medium. We compute the H2 and CO abundances using a subgrid post-processing model based on the dust abundance and the dissociating radiation field calculated in the simulation. We find that when the metallicity is ≲ 0.4 Z⊙ (t 
ISSN:0035-8711
1365-2966
DOI:10.1093/mnras/stx2863