Evolution of the IR Energy Density and SFH up to Z ∼ 1: First Results from MIPS

Abstract

Using deep observations of the Chandra Deep Field South obtained with MIPS at 24 µm, we present our preliminary estimates on the evolution of the infrared (IR) luminosity density of the Universe from z=0 to z∼1. We find that a pure density evolution of the IR luminosity function is clearly excluded by the data. The characteristic luminosity LIR* evolves at least by (1+z) 3.5 with lookback time, but our monochromatic approach does not allow us to break the degeneracy between a pure evolution in luminosity or an evolution in both density and luminosity. Our results imply that IR luminous systems (LIR ≥ 10 11 L⊙) become the dominant population contributing to the comoving IR energy density beyond z ∼ 0.5-0.6. The uncertainties affecting our measurements are largely dominated by the poor constraints on the spectral energy distributions that are used to translate the observed 24 µm flux into luminosities.