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The formation and assembly of a typical star-forming galaxy at redshift z ≈ 3

Stark, Daniel P. and Swinbank, A. Mark and Ellis, Richard S. and Dye, Simon and Smail, Ian R. and Richard, Johan (2008) The formation and assembly of a typical star-forming galaxy at redshift z ≈ 3. Nature, 455 (7214). pp. 775-777. ISSN 0028-0836.

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Recent studies of galaxies ~2–3 Gyr after the Big Bang have revealed large, rotating disks, similar to those of galaxies today^(1,2). The existence of well-ordered rotation in galaxies during this peak epoch of cosmic star formation indicates that gas accretion is likely to be the dominant mode by which galaxies grow, because major mergers of galaxies would completely disrupt the observed velocity fields. But poor spatial resolution and sensitivity have hampered this interpretation; such studies have been limited to the largest and most luminous galaxies, which may have fundamentally different modes of assembly from those of more typical galaxies (which are thought to grow into the spheroidal components at the centres of galaxies similar to the Milky Way). Here we report observations of a typical star-forming galaxy at z = 3.07, with a linear resolution of ~100 parsecs. We find a well-ordered compact source in which molecular gas is being converted efficiently into stars, likely to be assembling a spheroidal bulge similar to those seen in spiral galaxies at the present day. The presence of undisrupted rotation may indicate that galaxies such as the Milky Way gain much of their mass by accretion rather than major mergers.

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Ellis, Richard S.0000-0001-7782-7071
Smail, Ian R.0000-0003-3037-257X
Additional Information:© 2009 Nature Publishing Group. Received 15 January 2008; Accepted 21 July 2008. We thank J. Lyke for assistance with the Keck observations, and R. Bower, K. Coppin, M. Lehnert, R. Genzel, D. Erb, D. Law, A. Shapley, A. Jenkins, P. Salucci and T. Theuns for discussions. The OSIRIS data were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership between the California Institute of Technology, the University of California and NASA. The observatory was made possible by the financial support of the W. M. Keck Foundation. The SINFONI data are based on observations made with the ESO Telescopes at the Paranal Observatories. A.M.S. acknowledges financial support from STFC, and I.R.S. and R.S.E. acknowledge financial support from the Royal Society.
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W. M. Keck FoundationUNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
Issue or Number:7214
Record Number:CaltechAUTHORS:20090520-125544934
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14279
Deposited By: Tony Diaz
Deposited On:26 Aug 2009 22:18
Last Modified:26 Nov 2019 11:15

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