2007/10/10 by Jeffrey G. Mangum, J. G. Mangum, Jeremy Darling +4 · 2 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Galaxy #Luminosity #Luminous infrared galaxy #Physics #Star formation #Stars #Stellar mass #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/524354
Accepted ApJ; 16 pages, 12 figures, 7 tables, emulateapj formatting
arxiv created 2007/10/10 · openalex publication_date 2008/02/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
With a goal toward deriving the physical conditions in external galaxies, we present a survey of the formaldehyde emission in a sample of starburst systems. By extending a technique used to derive the spatial density in star formation regions in our own Galaxy, we show how the relative intensity of the 1 10 -1 11 and 2 11 -2 12 K -doublet transitions of H 2 CO can provide an accurate densitometer for the active star formation environments found in starburst galaxies. Relying on an assumed kinetic temperature and cospatial emission and absorption from both H 2 CO transitions, our technique is applied to a sample of 19 infrared-bright galaxies which exhibit various forms of starburst activity. In the five galaxies of our sample where both H 2 CO transitions were detected, we have derived spatial densities. We also use H 2 CO to estimate the dense gas mass in our starburst galaxy sample, finding similar mass estimates for the dense gas-forming stars in these objects as derived using other dense gas tracers. A related trend can be seen when one compares L IR to our derived n (H 2 ) for the five galaxies within which we have derived spatial densities. Even though our number statistics are small, there appears to be a trend toward higher spatial density for galaxies with higher infrared luminosity. This is likely another representation of the L IR - M dense correlation.