1. Revisiting the Extended Schmidt Law: The Important Role of Existing Stars in Regulating Star Formation
- Author
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Qiusheng Gu, Stephen Gwyn, Jingwen Wu, Luwenjia Zhou, Yu Gao, George Helou, Lee Armus, Xianzhong Zheng, Sabrina Stierwalt, Junzhi Wang, Min Fang, Lin Yan, Yong Shi, Yanmei Chen, Zhi-Yu Zhang, and Keping Qiu
- Subjects
Stellar mass ,FOS: Physical sciences ,galaxies: starburst ,Astrophysics::Cosmology and Extragalactic Astrophysics ,ISM: atoms ,Galaxy merger ,Star (graph theory) ,01 natural sciences ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Dwarf galaxy ,Physics ,stars: formation ,010308 nuclear & particles physics ,Star formation ,Molecular cloud ,Astronomy and Astrophysics ,Astrophysics - Astrophysics of Galaxies ,ISM: molecules ,Galaxy ,Stars ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Law ,Astrophysics::Earth and Planetary Astrophysics ,galaxies: evolution - Abstract
We revisit the proposed extended Schmidt law (Shi et al. 2011) which points that the star formation efficiency in galaxies depends on the stellar mass surface density, by investigating spatially-resolved star formation rates (SFRs), gas masses and stellar masses of star formation regions in a vast range of galactic environments, from the outer disks of dwarf galaxies to spiral disks and to merging galaxies as well as individual molecular clouds in M33. We find that these regions are distributed in a tight power-law as Sigma_SFR ~(Sigma_star^0.5 Sigma_gas )^1.09, which is also valid for the integrated measurements of disk and merging galaxies at high-z. Interestingly, we show that star formation regions in the outer disks of dwarf galaxies with Sigma_SFR down to 10^(-5) Msun/yr/kpc^2, which are outliers of both Kennicutt-Schmidt and Silk-Elmegreen law, also follow the extended Schmidt law. Other outliers in the Kennicutt-Schmidt law, such as extremely-metal poor star-formation regions, also show significantly reduced deviations from the extended Schmidt law. These results suggest an important role for existing stars in helping to regulate star formation through the effect of their gravity on the mid-plane pressure in a wide range of galactic environments., Comment: 15 pages, 6 figures, 3 tables; ApJ in press
- Published
- 2018