2010A&A...512A..78B

We aim to place stronger lower limits on the cosmic infrared background (CIB) brightness at 24µm, 70µm and 160µm and measure the extragalactic number counts at these wavelengths in a homogeneous way from various surveys. Using Spitzer legacy data over 53.6deg² of various depths, we build catalogs with the same extraction method at each wavelength. Completeness and photometric accuracy are estimated with Monte-Carlo simulations. Number count uncertainties are estimated with a counts-in-cells moment method to take galaxy clustering into account. Furthermore, we use a stacking analysis to estimate number counts of sources not detected at 70µm and 160µm. This method is validated by simulations. The integration of the number counts gives new CIB lower limits. Number counts reach 35µJy, 3.5mJy and 40mJy at 24µm, 70µm, and 160µm, respectively. We reach deeper flux densities of 0.38mJy at 70, and 3.1 at 160µm with a stacking analysis. We confirm the number count turnover at 24µm and 70µm, and observe it for the first time at 160µm at about 20mJy, together with a power-law behavior below 10mJy. These mid- and far-infrared counts: 1) are homogeneously built by combining fields of different depths and sizes, providing a legacy over about three orders of magnitude in flux density; 2) are the deepest to date at 70µm and 160µm; 3) agree with previously published results in the common measured flux density range; 4) globally agree with the Lagache et al. (2004ApJS..154..112L) model, except at 160µm, where the model slightly overestimates the counts around 20 and 200mJy. These counts are integrated to estimate new CIB firm lower limits of 2.29_–0.09^+0.09nW/m²/sr, 5.4_–0.4^+0.4nW/m²/sr, and 8.9_–1.1^+1.1nW/m²/sr at 24µm, 70µm, and 160µm, respectively, and extrapolated to give new estimates of the CIB due to galaxies of 2.86_–0.16^+0.19nW/m²/sr, 6.6_–0.6^+0.7nW/m²/sr, and 14.6_–2.9^+7.1nW/m²/srl, respectively. Products (point spread function, counts, CIB contributions, software) are publicly available for download at url http://www.ias.u-psud.fr/irgalaxies/