TY - JOUR
T1 - First results from the 3D-HST survey
T2 - The striking diversity of massive galaxies at z > 1
AU - Van Dokkum, Pieter G.
AU - Brammer, Gabriel
AU - Fumagalli, Mattia
AU - Nelson, Erica
AU - Franx, Marijn
AU - Rix, Hans Walter
AU - Kriek, Mariska
AU - Skelton, Rosalind E.
AU - Patel, Shannon
AU - Schmidt, Kasper B.
AU - Bezanson, Rachel
AU - Bian, Fuyan
AU - Da Cunha, Elisabete
AU - Erb, Dawn K.
AU - Fan, Xiaohui
AU - Förster Schreiber, Natascha
AU - Illingworth, Garth D.
AU - Labbé, Ivo
AU - Lundgren, Britt
AU - Magee, Dan
AU - Marchesini, Danilo
AU - McCarthy, Patrick
AU - Muzzin, Adam
AU - Quadri, Ryan
AU - Steidel, Charles C.
AU - Tal, Tomer
AU - Wake, David
AU - Whitaker, Katherine E.
AU - Williams, Anna
PY - 2011/12/10
Y1 - 2011/12/10
N2 - 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 Hα) 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 EWHα >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.
AB - 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 Hα) 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 EWHα >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.
KW - cosmology: observations
KW - galaxies: evolution
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U2 - 10.1088/2041-8205/743/1/L15
DO - 10.1088/2041-8205/743/1/L15
M3 - Review article
AN - SCOPUS:82355165146
SN - 2041-8205
VL - 743
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - L15
ER -