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 mu m imaging of the GOODS-North field. The 70 mu m 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 S-70 > 2 mJy (S/N > 3 sigma). The majority (81%) of the sources have spectroscopic redshifts, and photometric redshifts are calculated for the remainder. The IR luminosity function at four redshifts (z similar to 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 rho(L, z) = (1+ z)(q) rho(L/(1 + Z)(p),0), we find q = -2.19p + 6.09. In the case of pure luminosity evolution, we find a best fit of p = 2.78(-0.32)(+0.34). This is consistent with the results from 24 mu m 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-circle dot) population for z < 0.4.