2011A&A...528A..35M

We derive the evolution of the infrared luminosity function (LF) over the last 4/5ths of cosmic time using deep 24 and 70µm imaging of the GOODS North and South fields. We use an extraction technique based on prior source positions at shorter wavelengths to build the 24 and 70µm source catalogs. The majority (93%) of the sources have a spectroscopic (39%) or a photometric redshift (54%) and, in our redshift range of interest (i.e., 1.3<z<2.3) s20% of the sources have a spectroscopic redshift. To extend our study to lower 70µm luminosities we perform a stacking analysis and we characterize the observed L_24/(1+z) vs. L_70/(1+z) correlation. Using spectral energy distribution (SED) templates which best fit this correlation, we derive the infrared luminosity of individual sources from their 24 and 70µm luminosities. We then compute the infrared LF at zs1.55 ±0.25 and zs2.05±0.25. We observe the break in the infrared LF up to zs2.3. The redshift evolution of the infrared LF from z=1.3 to z=2.3 is consistent with a luminosity evolution proportional to (1+z)^1.0±0.9 combined with a density evolution proportional to (1+z)^–1.1±1.5. At zs2, luminous infrared galaxies (LIRGs: 10¹¹L_☉<L_IR<10¹²L_☉) are still the main contributors to the total comoving infrared luminosity density of the Universe. At zs2, LIRGs and ultra-luminous infrared galaxies (ULIRGs: 10¹²L_☉<L_IR) account for s49% and s17% respectively of the total comoving infrared luminosity density of the Universe. Combined with previous results using the same strategy for galaxies at z<1.3 and assuming a constant conversion between the infrared luminosity and star-formation rate (SFR) of a galaxy, we study the evolution of the SFR density of the Universe from z=0 to z=2.3. We find that the SFR density of the Universe strongly increased with redshift from z=0 to z=1.3, but is nearly constant at higher redshift out to z=2.3. As part of the online material accompanying this article, we present source catalogs at 24µm and 70µm for both the GOODS-North and -South fields.