Large Disklike Galaxies at High Redshift

Labbé, Ivo; Rudnick, Gregory; Franx, Marijn; Daddi, Emanuele; van Dokkum, Pieter G.; Förster Schreiber, Natascha M.; Kuijken, Konrad; Moorwood, Alan; Rix, Hans-Walter; Röttgering, Huub; Trujillo, I.; van der Wel, Arjen; van der Werf, Paul; van Starkenburg, Lottie
Referencia bibliográfica

The Astrophysical Journal, Volume 591, Issue 2, pp. L95-L98.

Fecha de publicación:
7
2003
Número de autores
14
Número de autores del IAC
0
Número de citas
76
Número de citas referidas
68
Descripción
Using deep near-infrared imaging of the Hubble Deep Field-South with the Infrared Spectrometer and Array Camera on the Very Large Telescope, we find six large disklike galaxies at redshifts z=1.4-3.0. The galaxies, selected in Ks (2.2 μm), are regular and surprisingly large in the near-infrared (rest-frame optical), with face-on effective radii re=0.65"-0.9" or 5.0-7.5 h-170 kpc in a Λ cold dark matter cosmology, comparable to the Milky Way. The surface brightness profiles are consistent with an exponential law over 2-3 effective radii. The Wide Field Planetary Camera 2 morphologies in Hubble Space Telescope imaging (rest-frame UV) are irregular and show complex aggregates of star-forming regions ~2" (~15 h-170 kpc) across, symmetrically distributed around the Ks-band centers. The spectral energy distributions show clear breaks in the rest-frame optical. The breaks are strongest in the central regions of the galaxies and can be identified as the age-sensitive Balmer/4000 Å break. The most straightforward interpretation is that these galaxies are large disk galaxies; deep near-infrared data are indispensable for this classification. The candidate disks constitute 50% of galaxies with LV>~6×1010 h-270 Lsolar at z=1.4-3.0. This discovery was not expected on the basis of previously studied samples. In particular, the Hubble Deep Field-North is deficient in large galaxies with the morphologies and profiles we report here. Based on service mode observations collected at the European Southern Observatory, Paranal, Chile (ESO programme 164.O-0612) and also based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555.