The Far-Infrared Luminosity Function from GOODS-North: Constraining the Evolution of Infrared Galaxies for z ≤ 1

Abstract

We present the IR luminosity function derived from ultradeep 70 μm imaging of the GOODS-North field. The 70 μm observations are longward of the PAH and silicate features which complicate work in the MIR. We derive far-infrared luminosities for the 143 sources with S70 > 2 mJy (S/N > 3σ). The majority (81%) of 70 the sources have spectroscopic redshifts, and photometric redshifts are calculated for the remainder. The IR luminosity function at four redshifts (z ∼ 0.28, 0.48, 0.78, and 0.97) is derived and compared to the local one. There is considerable degeneracy between luminosity and density evolution. If the evolving luminosity function is described as ρ(L,z) = (1+z)^q ρ(L/(1+z)^p, 0, we find q = -2.19p + 6.09. In the case of pure luminosity p = 2.78 +0.34 -0.32. This is consistent with the results from 24 μm and 1.4 GHz studies. Our results confirm the emerging picture of strong evolution in LIRGs and ULIRGs at 0.4 < z < 1.1, but we find no evidence of significant evolution in the sub-LIRG (L < 10^11 L☉) population for z < 0.4.