Modeling the evolution of infrared galaxies: clustering of galaxies in the cosmic infrared background

¹ Univ. Paris Sud, Institut d’Astrophysique Spatiale, UMR8617, 91405 Orsay, France
e-mail: aurelie.penin@ias.u-psud.fr
² CNRS, 91405 Orsay, France
³ Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
⁴ California Institute of Technology, Pasadena, CA 91125, USA

Received: 16 June 2011
Accepted: 25 September 2011

Abstract

Context. Star-forming galaxies are highly biased tracers of the underlying dark matter density field. Their clustering can be studied through the cosmic infrared background (CIB) anisotropies. These anisotropies have been measured from 100 μm to 2 mm in the past few years.

Aims. In this paper, we present a fully parametric model allowing joint analysis of these recent observations.

Methods. 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 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 halos of different masses and redshifts and how LIRGs and ULIRGs contribute to the CIB angular power spectra.

Results. 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_ℓ, counts, and luminosity functions improves the constraints slightly but does not remove any degeneracies. In contrast, 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. Our framework allows a coherent and joint analysis of various probes of infrared galaxies: number counts, luminosity functions, and clustering measurements; however, such a model has a few limitations, such as the parameters of the halo occupation that suffer from strong degeneracies.