Dense Gas, Chemistry and Star Formation in Luminous Galaxies
Author: Aalto, Susanne
Source: Astrophysics and Space Science, Volume 295, Numbers 1-2, January 2005 , pp. 143-153(11)
Abstract:The molecular phase of the ISM constitutes the main source of fuel for the activity in starburst and AGNs. The physical conditions and chemical constitution of the molecular gas will change with, and respond to, the evolution of the activity. This paper includes a short discussion of the 12CO/13CO 1–0 line intensity ratio as a diagnostic tool of the molecular gas properties of luminous galaxies – paired with examples of high-resolution studies of how the line ratio varies within galaxies. A possible connection between the OH megamasers and galaxies with unusually high 12CO/13CO 1–0 line intensity ratios are also briefly discussed.
The relative intensities of the dense gas tracers HNC, HCN, HCO+ and CN are a result of both chemistry and starburst evolution. The discussion on the interpretation of HNC 1–0 emission includes the importance of ion-neutral chemistry in a luminous starburst region. Finally, simple cartoon ISM models and how they can be applied to LIRGs and ULIRGs, are presented.
Document Type: Research Article
Affiliations: Onsala Rymdobservatorium, Chalmers Tekniska Högskola, Onsala, Sweden, Email: firstname.lastname@example.org
Publication date: January 1, 2005