1. Department of Physics & Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218-2686, USA
2. Department of Astronomy & Astrophysics, University of Toronto, 60 St George Street, Toronto, Ontario M5S 3H8, Canada
3. Observatories of the Carnegie Institute of Washington, Santa Barbara Street, Pasadena, California 9110, USA
4. Center for Space Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA
5. Herzberg Institute of Astrophysics, National Research Council, 5071 West Saanich Road, Victoria, British Columbia, V9E 2E7, Canada
6. Gemini Observatory, Hilo, Hawaii 96720, USA
7. Department of Astrophysics, Nuclear & Astrophysics Laboratory, Oxford University, Keble Road, Oxford OX1 3RH, UK
8. Department of Physics and Astronomy, San Francisco State University, 1600 Holloway Avenue, San Francisco, California 94132, USA

Correspondence to: Karl Glazebrook¹ Email: kgb@pha.jhu.edu

Abstract

Hierarchical galaxy formation is the model whereby massive galaxies form from an assembly of smaller units¹. The most massive objects therefore form last. The model succeeds in describing the clustering of galaxies², but the evolutionary history of massive galaxies, as revealed by their visible stars and gas, is not accurately predicted. Near-infrared observations (which allow us to measure the stellar masses of high-redshift galaxies³) and deep multi-colour images indicate that a large fraction of the stars in massive galaxies form in the first 5 Gyr (refs 4–7), but uncertainties remain owing to the lack of spectra to confirm the redshifts (which are estimated from the colours) and the role of obscuration by dust. Here we report the results of a spectroscopic redshift survey that probes the most massive and quiescent galaxies back to an era only 3 Gyr after the Big Bang. We find that at least two-thirds of massive galaxies have appeared since this era, but also that a significant fraction of them are already in place in the early Universe.

1. Department of Physics & Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218-2686, USA
2. Department of Astronomy & Astrophysics, University of Toronto, 60 St George Street, Toronto, Ontario M5S 3H8, Canada
3. Observatories of the Carnegie Institute of Washington, Santa Barbara Street, Pasadena, California 9110, USA
4. Center for Space Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA
5. Herzberg Institute of Astrophysics, National Research Council, 5071 West Saanich Road, Victoria, British Columbia, V9E 2E7, Canada
6. Gemini Observatory, Hilo, Hawaii 96720, USA
7. Department of Astrophysics, Nuclear & Astrophysics Laboratory, Oxford University, Keble Road, Oxford OX1 3RH, UK
8. Department of Physics and Astronomy, San Francisco State University, 1600 Holloway Avenue, San Francisco, California 94132, USA

Correspondence to: Karl Glazebrook¹ Email: kgb@pha.jhu.edu

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