The Molecular ISM of Low Surface Brightness Spiral Galaxies

Abstract

I summarize some results from the recent CO survey of late-type, low surface brightness (LSB) spiral galaxies by Matthews et al. (2005). We have now detected CO emission from six late-type, LSB spirals, demonstrating that despite their typical low metallicities and low mean gas surface densities, some LSB galaxies contain a molecular medium that is traced by CO. We find that the CO-detected LSB spirals adhere to the same M_H2-FIR correlation as brighter galaxies. We also find a significant drop-off in the detectability of CO among low-to-intermediate surface brightness galaxies with V_rot<~90 km/s, pointing toward fundamental changes in the physical conditions of the ISM with decreasing disk mass.

6 pages; to appear in the proceedings "Island Universes - Structure and Evolution of Disk Galaxies", a conference held in Terschelling, the Netherlands, July 2005, R. S. de Jong, editor, (Springer: Dordrecht)

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• Detections of CO in Late-Type, Low Surface Brightness Spiral Galaxies
• Properties of Molecular Gas in Massive Low Surface Brightness Galaxies, Including New 12CO Observations of Three Malin 1 `Cousins'