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Yu Gao, E. Seaquist (University of Toronto), K.Y. Lo (IAA, Academia Sinica)
We explore the sample properties of luminous infrared galaxy mergers (LIGMs) in the nearby Bright Galaxy Sample and argue that LIGMs as a whole serve as a natural sample to investigate the role of mergers in triggering large scale star formation in gas-rich merging galaxies.
Compared to the optically selected samples of the interacting galaxies, particularly the representative Toomre Sequence, from the observational point of view, LIGMs are the better sample one can gather to statistically trace an entire merger sequence of gas-rich galaxies leading to the ultraluminous extreme starbursts. This is simply because all LIGMs are gas-rich and their initial gas content might be comparable, whereas this is clearly not true for the optically selected interacting galaxies.
We summarize the various supportive evidence reflecting the merging sequence, both globally and locally, from currently still limited small number of LIGMs studied: e.g., the total gas content; gas surface density; fraction of dense gas; extent/morphology of gas and stars; various infrared properties and radio continuum imaging; and sub-millimeter SCUBA observations etc. Studying such a large, statistically significant and complete sample of LIGMs will constrain tremendously both the merger-induced starburst models and the understanding of the star formation, galaxy formation and evolution in general.
The author(s) of this abstract have provided an email address for comments about the abstract: gao@astro.utoronto.ca