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| Paper: |
A Molecular Gas Phase in the Cold Neutral Medium? |
| Volume: |
320, The Neutral ISM in Starburst Galaxies |
| Page: |
101 |
| Authors: |
Papadopoulos, P. |
| Abstract: |
I examine the possibility that the Cold Neutral Medium of the interstellar medium in galaxies contains a molecular gas phase that may represent a significant and even the dominant amount of its mass in metal-poor regions. In spiral galaxies such regions are found at large galactocentric distances where diffuse H2 gas will be untraceable through its feeble 12CO J=1−0 emission, the very lack of it being also responsible for its higher kinetic temperatures (Tk ∼ 60 − 100 K). Sensitive sub-mm imaging of spiral galaxies has demonstrated the existence of dust well inside their HI gas distribution while recent observational work suggests a high H2 formation rate from HI association onto grains. The latter is indeed a critical unknown and a high value can easily compensate for the reduction of the available grain surface in the metal-poor environments giving rise to a CO-poor, diffuse H2 phase that may then contribute significantly to the mass and pressure of the interstellar medium in such environments. |
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