The infrared luminosity function of galaxies at redshifts z=1 and z=2 in the GOODS fields

We present the rest-frame 8 mu m LF at redshifts z = 1 and similar to 2, computed from Spitzer 24 mu m-selected galaxies in the GOODS fields over an area of 291 arcmin(2). Using classification criteria based on X-ray data and IRAC colors, we identify the AGNs in our sample. The rest-frame 8 mu m LFs for star-forming galaxies at redshifts z = 1 and similar to 2 have the same shape as at z similar to 0, but with a strong positive luminosity evolution. The number density of star-forming galaxies with log(10)(nu L-nu(8 mu m)) > 11 increases by a factor > 250 from redshift z similar to 0 to 1 and is basically the same at z = 1 and similar to 2. The resulting rest-frame 8 mu m luminosity densities associated with star formation at z - 1 and similar to 2 are more than 4 and 2 times larger than at z similar to 0, respectively. We also compute the total rest-frame 8 mu m LF for star-forming galaxies and AGNs at z similar to 2 and show that AGNs dominate its bright end, which is well described by a power law. Using a new calibration based on Spitzer star-forming galaxies at 0 <z <0: 6 and validated at higher redshifts through stacking analysis, we compute the bolometric IR LF for star-forming galaxies at z = 1 and similar to 2. We find that the respective bolometric IR luminosity densities are (1.2 +/- 0.2); 10(9) and (6.6(-1.0)(+1.2)) x 10(8) L circle dot Mpc(-3), in agreement with previous studies within the error bars. At z similar to 2, around 90% of the IR luminosity density associated with star formation is produced by luminous and ultraluminous IR galaxies, with the two populations contributing in roughly similar amounts. Finally, we discuss the consistency of our findings with other existing observational results on galaxy evolution.