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Different Star Formation Laws for Disks Versus Starbursts at Low and High Redshifts

Daddi, E. and Elbaz, D. and Walter, F. and Bournaud, F. and Salmi, F. and Carilli, C. L. and Dannerbauer, H. and Dickinson, M. and Monaco, P. and Riechers, D. (2010) Different Star Formation Laws for Disks Versus Starbursts at Low and High Redshifts. Astrophysical Journal Letters, 714 (1). L118-L122. ISSN 2041-8205.

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We present evidence that bona fide disks and starburst systems occupy distinct regions in the gas mass versus star formation rate (SFR) plane, both for the integrated quantities and for the respective surface densities. This result is based on carbon monoxide (CO) observations of galaxy populations at low and high redshifts, and on the current consensus for the CO luminosity to gas mass conversion factors. The data suggest the existence of two different SF regimes: a long-lasting mode for disks and a more rapid mode for starbursts, the latter probably occurring during major mergers or in dense nuclear SF regions. Both modes are observable over a large range of SFRs. The detection of CO emission from distant near-IR selected galaxies reveals such bimodal behavior for the first time, as they allow us to probe gas in disk galaxies with much higher SFRs than are seen locally. The different regimes can potentially be interpreted as the effect of a top-heavy initial mass function in starbursts. However, we favor a different physical origin related to the fraction of molecular gas in dense clouds. The IR luminosity to gas mass ratio (i.e., the SF efficiency) appears to be inversely proportional to the dynamical (rotation) timescale. Only when accounting for the dynamical timescale, a universal SF law is obtained, suggesting a direct link between global galaxy properties and the local SFR.

Item Type:Article
Related URLs:
URLURL TypeDescription
Daddi, E.0000-0002-3331-9590
Elbaz, D.0000-0002-7631-647X
Walter, F.0000-0003-4793-7880
Carilli, C. L.0000-0001-6647-3861
Dannerbauer, H.0000-0001-7147-3575
Dickinson, M.0000-0001-5414-5131
Riechers, D.0000-0001-9585-1462
Additional Information:© 2010 The American Astronomical Society. Received 2009 December 17; accepted 2010 March 22; published 2010 April 5. We thank Adam Leroy for discussions and help with Figure 2 and Padelis Papadopoulos for discussions. We acknowledge the funding support of the ERC-StG grant UPGAL-240039, ANR-07-BLAN-0228, and ANR-08-JCJC-0008. D.R. acknowledges NASA Hubble Fellowship grant HST-HF-51235.01 awarded by the STScI, operated by AURA for NASA, contract NAS-5-26555.
Funding AgencyGrant Number
European Research Council (ERC)UPGAL-240039
Agence Nationale pour la Recherche (ANR)ANR- 07-BLAN-0228
Agence Nationale pour la Recherche (ANR)ANR-08-JCJC-0008
NASA Hubble FellowshipHST-HF-51235.01
Subject Keywords:cosmology: observations – galaxies: evolution – galaxies: formation – galaxies: starburst – infrared: galaxies
Issue or Number:1
Classification Code:PACS: 97.10.Bt; 98.54.Ep; 98.62.Py; 98.62.Hr; 98.62.Lv; 98.58.Db
Record Number:CaltechAUTHORS:20100521-072211251
Persistent URL:
Official Citation:E. Daddi et al 2010 ApJ 714 L118 doi: 10.1088/2041-8205/714/1/L118
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:18381
Deposited By: Ruth Sustaita
Deposited On:21 May 2010 20:25
Last Modified:09 Mar 2020 13:18

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