Molecular Gas and Star Formation in Dwarf Galaxies Observed by the Atacama Large Millimeter/submillimeter Array
Abstract
We present a spatially resolved analysis of the molecular star formation law (SFL) and gravitational instability in a sample of nearby dwarf galaxies (NGC 1035, NGC 4310, NGC 4451, NGC 4701, NGC 5692, and NGC 6106), using high-resolution 12CO (J=1→0) data from the Atacama Large Millimeter/submillimeter Array. We estimate the star formation rate (SFR) by combining the Galaxy Evolution Explorer near-ultraviolet and the Wide-field Infrared Survey Explorer 12 μm imaging data to examine the relationship between molecular gas and SFR densities on scales of several hundred parsecs. We find that the power-law slope of the molecular SFL ranges from 0.62 to 1.08, with an average value of N=0.810.18, increasing to N=0.870.05 when excluding galaxies with poorly constrained CO data. These results are roughly consistent with values observed in massive spiral galaxies, suggesting a universal molecular SFL when analyzed with sufficient resolution and sensitivity. Radial profiles of the Toomre Q parameter remain close to unity across the disks, with minimal radial variation, consistent with a self-regulated star formation model. Our results suggest that, despite their lower mass and metallicity, star formation in dwarf galaxies is governed by the same fundamental physical processes as in larger systems. This highlights the significance of high-resolution molecular gas observations in low-mass galaxies.
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