Large disklike galaxies at high redshift

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. The galaxies, z = 1.4 - 3.0 selected in K-s (2.2 mum), are regular and surprisingly large in the near-infrared (rest-frame optical), with face-on effective radii r(e) = 0."65-0."9 or 5.0 - 7.5 h(70)(-1) kpc in a Lambda 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 similar to2" (similar to15 h(70)(-1) kpc) across, symmetrically distributed around the K-s-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 Angstrom 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 at L-v greater than or similar to 6 x 10(10) h(70)(-2) L-. at z = 1.4- 30. This discovery was not expected on the basis of previously studied samples. In particular, the Hubble Deep 3.0 Field - North is deficient in large galaxies with the morphologies and profiles we report here.