HDFS IRAC observations of 2<z<3.5 galaxies

The sample is selected from the deepest public K-band imaging currently available. We show that the rest-frame U-V versus V-J color-color diagram is a powerful diagnostic of the stellar populations of distant galaxies.

Galaxies with red rest-frame U-V colors are generally red in rest-frame V-J as well. However, at a given U-V color a range in V-J colors exists, and we show that this allows us to distinguish young, dusty galaxies from old, passively evolving galaxies. We quantify the effects of IRAC photometry on estimates of masses, ages, and the dust content of z>2 galaxies.