Radial profiles of stellar disks in galaxies atz≈1 from the udf and the goods fields

Abstract

Following the finding that a number of stellar disks at redshift ≈1 show radial profiles best fit by a double exponential (Pérez 2004), we have carried out a campaign to derive the radial profiles of a sample of galaxies from the Ultra Deep Field (UDF). Of the 19 UDF galaxies, six show double exponential profiles. The results are compatible with the previous study and there is no clear evidence for disk evolution. However, we do not detect any galaxy with a break radius larger than 2.5 scale-lengths, unlike the local galaxies where breaks are found up to around 4 scale-lengths. The colours of the truncated galaxies seem to be bluer than those of ‘untruncated’ galaxies, suggesting a younger population. The ratio between the inner and the outer scale-length is 2.0±0.5 in agreement with the results from the previous sample from GOODS data.