Modeling the evolution of infrared galaxies : clustering of galaxies in the Cosmic Infrared Background

Abstract

Star-forming galaxies are a highly biased tracer of the underlying dark matter density field. Their clustering can be studied through the cosmic infrared background anisotropies. These anisotropies have been measured from 100 \mum to 2 mm in the last few years. In this paper, we present a fully parametric model allowing a joint analysis of these recent observations. In order to develop a coherent model at various wavelengths, we rely on two building blocks. The first one is a parametric model that describes the redshift evolution of the luminosity function of star-forming galaxies. It compares favorably to measured differential number counts and luminosity functions. The second one is a halo model based description of the clustering of galaxies. Starting from a fiducial model, we investigate parameter degeneracies using a Fisher analysis. We then discuss how halo of different mass and redshift, how LIRGs and ULIRGs, contribute to the CIB angular power spectra. From the Fisher analysis, we conclude that we cannot constrain the parameters of the model of evolution of galaxies using clustering data only. The use of combined data of C\ell, counts and luminosity functions improves slightly the constraints but does not remove any degeneracies. On the contrary, the measurement of the anisotropies allows us to set interesting constraints on the halo model parameters, even if some strong degeneracies remain. Using our fiducial model, we establish that the 1-halo and 2-halo terms are not sensitive to the same mass regime. We also illustrate how the 1-halo term can be misinterpreted with the Poisson noise term. Conclusions. We present a new model of the clustering of infrared galaxies. However such a model has a few limitations, as the parameters of the halo occupation suffer from strong degeneracies.