We investigate the multi-wavelength emission of BzK selected star forming
galaxies at z~2 in the Great Observatories Origins Deep Survey (GOODS) North
region. Most (82%) of the sources are individually detected at 24um in the
Spitzer MIPS imaging, and one fourth (26%) in the VLA radio data. Significant
detections of the individually undetected objects are obtained through stacking
in the radio, submm and X-ray domains. The typical star forming galaxy with
stellar mass ~10^{11}Mo at z=2 is an Ultra-luminous Infrared Galaxy (ULIRG),
with L_IR ~ 1-2x10^{12}Lo and star formation rate SFR 200-300Mo/yr, implying a
comoving density of ULIRGs at z=2 at least 3 orders of magnitude above the
local one. SFRs derived from the reddening corrected UV luminosities agree
well, on average, with the longer wavelength estimates. The high 24um detection
rate suggests a relatively large duty cycle for the BzK star forming phase,
consistently with the available independent measurements of the space density
of passively evolving galaxies at z>1.4. If the IMF at z=2 is similar to the
local one, and in particular is not a top-heavy IMF, this suggests that a
substantial fraction of the high mass tail (>10^{11}Mo) of the galaxy stellar
mass function was completed by z~1.4.Comment: 4 pages, 2 figures, ApJ Letters in pres