Revisiting the Extended Schmidt Law: The Important Role of Existing Stars in Regulating Star Formation
AffiliationUniv Arizona, Steward Observ
Univ Arizona, Dept Astron
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PublisherIOP PUBLISHING LTD
CitationRevisiting the Extended Schmidt Law: The Important Role of Existing Stars in Regulating Star Formation 2018, 853 (2):149 The Astrophysical Journal
JournalThe Astrophysical Journal
Rights© 2018. The American Astronomical Society. All rights reserved.
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AbstractWe revisit the proposed extended Schmidt law, which posits 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) proportional to (Sigma(0.5)(star)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) M(circle dot)yr(-1) kpc(-2), which are outliers of both the Kennicutt-Schmidt and Silk-Elmegreen laws, 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 deviation 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 midplane pressure in a wide range of galactic environments.
VersionFinal published version
SponsorsNational Key R&D Program of China [2017YFA0402704]; National Natural Science Foundation of China (NSFC) [11773013, 11733002, 11373021]; Excellent Youth Foundation of the Jiangsu Scientific Committee [BK20150014]; NSFC [11473011, 11590781]; Association of Universities for Research in Astronomy, Inc. under NASA [NAS 5-26555]; ALMA [2011.0.00182.S]; Smithsonian Institution; Academia Sinica