First results from the 3D-HST survey: The striking diversity of massive galaxies at z > 1

Pieter G. Van Dokkum, Gabriel Brammer, Mattia Fumagalli, Erica Nelson, Marijn Franx, Hans Walter Rix, Mariska Kriek, Rosalind E. Skelton, Shannon Patel, Kasper B. Schmidt, Rachel Bezanson, Fuyan Bian, Elisabete Da Cunha, Dawn K. Erb, Xiaohui Fan, Natascha Förster Schreiber, Garth D. Illingworth, Ivo Labbé, Britt Lundgren, Dan MageeDanilo Marchesini, Patrick McCarthy, Adam Muzzin, Ryan Quadri, Charles C. Steidel, Tomer Tal, David Wake, Katherine E. Whitaker, Anna Williams

Research output: Contribution to journalReview articlepeer-review

104 Scopus citations


We present first results from the 3D-HST program, a near-IR spectroscopic survey performed with the Wide Field Camera 3 (WFC3) on the HST. We have used 3D-HST spectra to measure redshifts and Hα equivalent widths (EW ) for a complete, stellar mass-limited sample of 34 galaxies at 1 < z < 1.5 with M star > 1011M in the COSMOS, GOODS, and AEGIS fields. We find that a substantial fraction of massive galaxies at this epoch are forming stars at a high rate: the fraction of galaxies with EW >10 is 59%, compared to 10% among Sloan Digital Sky Survey galaxies of similar masses at z = 0.1. Galaxies with weak Hα emission show absorption lines typical of 2-4Gyr old stellar populations. The structural parameters of the galaxies, derived from the associated WFC3 F140W imaging data, correlate with the presence of Hα; quiescent galaxies are compact with high Sérsic index and high inferred velocity dispersion, whereas star-forming galaxies are typically large two-armed spiral galaxies, with low Sérsic index. Some of these star-forming galaxies might be progenitors of the most massive S0 and Sa galaxies. Our results challenge the idea that galaxies at fixed mass form a homogeneous population with small scatter in their properties. Instead, we find that massive galaxies form a highly diverse population at z > 1, in marked contrast to the local universe.

Original languageEnglish (US)
Article numberL15
JournalAstrophysical Journal Letters
Issue number1
StatePublished - Dec 10 2011


  • cosmology: observations
  • galaxies: evolution

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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