The Luminosity Function of IRAS PSCz Galaxies

We estimated the luminosity function (LF) of IRAS galaxies in the PSCz catalogue. The faint end of the PSCz LF is slightly steeper than that of the LF derived by Saunders et al. (1990; S90). Using an analytical form for the LF used by S90, we obtain the following parameters: \alpha = 1.23 \pm 0.04, L_*=(8.85 \pm 1.75) \times 10^8 h^{-2} L_\odot, \sigma =0.724 \pm 0.010, and \phi_* = (2.34 \pm 0.30) \times 10^{-2} h^3 Mpc^{-3}. We also examined the evolution in the sample by a simple assumption \phi_*(z) \propto (1+z)^P, and found P=3.40 \pm 0.70. It does not affect the three parameters, \alpha, L_*, and \sigma, but \phi_*(z=0) is overestimated up to \sim 15% if we ignore evolution. We estimated the temperature dependence of the LF. The LFs of warm and cool galaxies are quite different: the LF of warm galaxies has a very steep faint end with \alpha =1.37. We also discuss a lump found at the brightest end of the LF.