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| Paper: |
Testing the Star Formation Law in Bulgeless Disk Galaxies |
| Volume: |
440, UP2010: Have Observations Revealed a Variable Upper End of the Initial Mass Function? |
| Page: |
393 |
| Authors: |
Watson, L.; Martini, P.; Böker, T.; Lisenfeld, U.; Schinnerer, E.; Wong, M.-H. |
| Abstract: |
We study the relation between the surface density of gas and star
formation rate in twenty bulgeless disk galaxies using data from the
IRAM 30m, MDM, Spitzer IRAC, and the VLA. Recent work has
provided constraints on the physics that sets the star formation
efficiency in varying environments of the interstellar medium;
however, a single theory for star formation has yet to stand out among
its peers. The general motivation for our study is to test the
predictive power of current theories with substantially improved
observations of late-type and low-mass disks, which are
underrepresented in most surveys. We specifically study star
formation and the properties of the cold and warm interstellar medium
above and below the circular velocity threshold of 120 km s-1 (stellar mass ~ 1010 M☉), where
Dalcanton et al. (2004) found that edge-on galaxies show an abrupt
transition in their dust scale heights. This transition also
corresponds to a disk stability transition according to the Toomre Q
parameter. In our sample, we find no difference between low-mass
(Vcirc < 120 km s–1) and high-mass (Vcirc > 120 km s–1) disks on the star formation
law, which indicates that the physical processes responsible for star
formation act on smaller scales than the tens of parsecs probed by
dust lanes. We also find that the correlation between the star
formation rate surface density and the total (atomic plus molecular)
gas surface density is stronger than either the atomic or molecular
correlation. |
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