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Extended Schmidt Law: Role of Existing Stars in Current Star Formation

Shi, Yong and Helou, George and Yan, Lin and Armus, Lee and Wu, Yanling and Papovich, Casey and Stierwalt, Sabrina (2011) Extended Schmidt Law: Role of Existing Stars in Current Star Formation. Astrophysical Journal, 733 (2). Art. No. 87. ISSN 0004-637X.

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We propose an "extended Schmidt law" with explicit dependence of the star formation efficiency (SFE = SFR/M _(gas)) on the stellar mass surface density (Σ_(star)). This relation has a power-law index of 0.48 ± 0.04 and a 1σ observed scatter on the SFE of 0.4 dex, which holds over five orders of magnitude in the stellar density for individual global galaxies, including various types and especially the low-surface-brightness (LSB) galaxies that deviate significantly from the Kennicutt-Schmidt (KS) law. When applying it to regions of a sample of 12 spiral galaxies at sub-kiloparsec resolution, the extended Schmidt law not only holds for LSB regions but also shows significantly smaller scatters both within and across galaxies compared with the KS law. We argue that this new relation points to the role of existing stars in regulating the SFE, thus better encoding the star formation physics. Comparison with physical models of star formation recipes shows that the extended Schmidt law can be reproduced by some models including gas free fall in a stellar-gravitational potential and pressure-supported star formation. By implementing this new law into the analytic model of gas accretion in ΛCDM, we show that it can reproduce the observed main sequence of star-forming galaxies (a relation between the SFR and stellar mass) from z = 0 up to z = 2.

Item Type:Article
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Yan, Lin0000-0003-1710-9339
Additional Information:© 2011 The American Astronomical Society. Received 2010 December 8; accepted 2011 March 22; published 2011 May 9. We thank the anonymous referee for the detailed and constructive comments.We also thank Daniel Dale, Leslie K. Hunt, Eva Schinnerer, and Bruce G. Elmegreen for careful reading and comments. The work is supported through the Spitzer 5MUSES Legacy Program 40539. The authors acknowledge support by NASA through awards issued by JPL/Caltech. This work was based on observations made with the Spitzer Space Telescope, which is operated by JPL/Caltech under a contract with NASA. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web site is
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Spitzer 5MUSES Legacy Program40539
Alfred P. Sloan FoundationUNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Japanese MonbukagakushoUNSPECIFIED
Max Planck SocietyUNSPECIFIED
Higher Education Funding Council for EnglandUNSPECIFIED
Subject Keywords:galaxies: evolution; galaxies: starburst; ISM: atoms; ISM: molecules; stars: formation
Issue or Number:2
Classification Code:PACS: 97.10.Bt; 98.54.Ep; 98.80.Cq; 98.62.Mw;
Record Number:CaltechAUTHORS:20110607-093056335
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Official Citation:Extended Schmidt Law: Role of Existing Stars in Current Star Formation Yong Shi, George Helou, Lin Yan, Lee Armus, Yanling Wu, Casey Papovich and Sabrina Stierwalt doi: 10.1088/0004-637X/733/2/87
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:23924
Deposited By: Ruth Sustaita
Deposited On:07 Jun 2011 16:50
Last Modified:03 Oct 2019 02:51

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