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Star Formation in AEGIS Field Galaxies since z = 1.1: The Dominance of Gradually Declining Star Formation, and the Main Sequence of Star-forming Galaxies

Noeske, K. G. and Weiner, B. J. and Faber, S. M. and Papovich, C. and Koo, D. C. and Somerville, R. S. and Bundy, K. and Conselice, C. J. and Newman, J. A. and Schiminovich, D. and Le Floc'h, E. and Coil, A. L. and Rieke, G. H. and Lotz, J. M. and Primack, J. R. and Barmby, P. and Cooper, M. C. and Davis, M. and Ellis, R. S. and Fazio, G. G. and Guhathakurta, P. and Huang, J. and Kassin, S. A. and Martin, D. C. and Phillips, A. C. and Rich, R. M. and Small, T. A. and Willmer, C. N. A. and Wilson, G. (2007) Star Formation in AEGIS Field Galaxies since z = 1.1: The Dominance of Gradually Declining Star Formation, and the Main Sequence of Star-forming Galaxies. Astrophysical Journal Letters, 660 (1). L43-L46. ISSN 2041-8205.

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We analyze star formation (SF) as a function of stellar mass (M☉) and redshift z in the All-Wavelength Extended Groth Strip International Survey. For 2905 field galaxies, complete to 10^10(10^10.8 )M at z < 0.7(1), with Keck spectroscopic redshifts out to z = 1.1, we compile SF rates (SFRs) from emission lines, GALEX, and Spitzer MIPS 24 µm photometry, optical-NIR M* measurements, and HST morphologies. Galaxies with reliable signs of SF form a distinct “main sequence” (MS), with a limited range of SFRs at a given M* and z (1 σ ≾ ±0.3 dex), and log (SFR) approximately proportional to log M*. The range of log (SFR) remains constant to z > 1, while the MS as a whole moves to higher SFR as z increases. The range of the SFR along the MS constrains the amplitude of episodic variations of SF and the effect of mergers on the SFR. Typical galaxies spend ∼67%(95%) of their lifetime since z = 1 within a factor of ≾2(4) of their average SFR at a given M* and z. The dominant mode of the evolution of SF since z ∼ 1 is apparently a gradual decline of the average SFR in most individual galaxies, not a decreasing frequency of starburst episodes, or a decreasing factor by which SFRs are enhanced in starbursts. LIRGs at z ∼ 1 seem to mostly reflect the high SFR typical for massive galaxies at that epoch. The smooth MS may reflect that the same set of few physical processes governs SF prior to additional quenching processes. A gradual process like gas exhaustion may play a dominant role.

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Ellis, R. S.0000-0001-7782-7071
Guhathakurta, P.0000-0001-8867-4234
Additional Information:© 2007. The American Astronomical Society. Received 2006 June 4; accepted 2007 January 31; published 2007 April 2. See the survey summary Letter (Davis et al. 2007) for full acknowledgments. This work is based on observations with the W.M. Keck Telescope, the Hubble Space Telescope, the Galaxy Evolution Explorer, the Canada-France-Hawaii Telescope, and the Palomar Observatory, and was supported by NASA and NSF grants. We wish to recognize the cultural role that the summit of Mauna Kea has within the Hawaiian community. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. Support for this work was provided by NASA through contract numbers 1256790, 960785, and 1255094 issued by JPL/Caltech. We wish to thank the referee for very valuable comments, and D. Elbaz and J. Lee for helpful discussions. K.G.N. acknowledges support from the Aspen Center for Physics. [J.A.N. and A.L.C. were] Hubble Fellow[s]. [J.M.L. was a] Leo Goldberg Fellow, National Optical Astronomy Observatory.
Group:Space Astrophysics Laboratory
Funding AgencyGrant Number
Aspen Center for PhysicsUNSPECIFIED
Hubble FellowshipUNSPECIFIED
National Optical Astronomy Observatory, Leo Goldberg FellowshipUNSPECIFIED
Subject Keywords:galactic evolution; galaxy formation; high-redshift galaxies; starburst
Record Number:CaltechAUTHORS:NOEapjl07a
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11402
Deposited By: Archive Administrator
Deposited On:12 Aug 2008 18:50
Last Modified:06 Oct 2017 00:18

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