What Controls the Star Formation in Luminous Starburst Mergers ?

Abstract

In order to understand what controls the star formation process in luminous starburst mergers (e.g., NGC 6240, Arp 220, and so on), we investigate observational properties of two samples of high-luminosity starburst galaxies mapped in CO($J$=1--0) independently using both the Owens Valley Radio Observatory (Scoville et al. 1991) and the IRAM interferometer (Downes & Solomon 1998). We find that the surface density of far-infrared luminosity, $\Sigma$(FIR), is proportional linearly to the H${}_2$ surface mass density, $\Sigma$(H${}_2$), for the two samples; $\Sigma$(FIR) $\propto \Sigma$(H${}_2$)${}^{1.01\pm 0.06}$ with a correlation coefficient of 0.96. It is often considered that $\Sigma$(FIR) provides a good measure of the star formation rate per unit area, $\Sigma$(SFR). It is also known that molecular gas is dominated in circumnuclear regions in the luminous starburst mergers; i.e., $\Sigma$(gas) $\simeq \Sigma$(H${}_2$). Therefore, the above relationship suggests a star formation law; $\Sigma$(SFR) $\propto \Sigma$(gas). We suggest that this star formation law favors the gravitational instability scenario rather than the cloud-cloud collision one.

14 pages, 2 figures. The Astrophysical Journal (Letters), in press

References in corpus (4)

• The Global Schmidt Law in Star Forming Galaxies
• Rotating Nuclear Rings and Extreme Starbursts in Ultraluminous Galaxies
• What Powers Ultra-luminous IRAS Galaxies?
• Starburst-driven Starbursts in the Heart of Ultraluminous Infrared Galaxies

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• Dynamical Masses in Luminous Infrared Galaxies
• A star formation study of the ATLAS3D early-type galaxies with the AKARI all-sky survey
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• Gas Distribution and Starburst Activity in the Widely Separated Interacting Galaxies NGC 6670
• Molecular gas budget of strongly magnified low-mass star-forming galaxies at cosmic noon