Modeling the evolution of infrared galaxies: a parametric backward evolution model

Abstract

Aims. We attempt to model the infrared galaxy evolution in as simple a way as possible and reproduce statistical properties such as the number counts between 15 μm and 1.1 mm, the luminosity functions, and the redshift distributions. We then use the fitted model to interpret observations from Spitzer, AKARI, BLAST, LABOCA, AzTEC, SPT, and Herschel, and make predictions for Planck and future experiments such as CCAT or SPICA. Methods. This model uses an evolution in density and luminosity of the luminosity function parametrized by broken power-laws with two breaks at redshift ∼0.9 and 2, and contains the two populations of the Lagache model: normal and starburst galaxies. We also take into account the effect of the strong lensing of high-redshift sub-millimeter galaxies. This effect is significant in the sub-mm and mm range near 50 mJy. It has 13 free parameters and eight additional calibration parameters. We fit the parameters to the IRAS, Spitzer, Herschel, and AzTEC measurements with a Monte Carlo Markov chain. Results. The model adjusted to deep counts at key wavelengths reproduces the counts from mid-infrared to millimeter wavelengths, as well as the mid-infrared luminosity functions. We discuss the contribution to both the cosmic infrared background (CIB) and the infrared luminosity density of the different populations. We also estimate the effect of the lensing on the number counts, and discuss the discovery by the South Pole Telescope (SPT) of a very bright population lying at high redshift. We predict the contribution of the lensed sources to the Planck number counts, the confusion level for future missions using a P(D) formalism, and the Universe opacity to TeV photons caused by the CIB. Material of the model (software, tables and predictions) is available online .

The cosmic far-infrared background buildup since redshift 2 at 70 and 160 microns in the COSMOS and GOODS fields

“…The Le Borgne et al (2009) model predicts a peak at lower redshift (z ≤ 0.5) and a strong contribution at z ∼ 0, neither of which seen in the data; otherwise, the decrease at z > 0.5 has a shape comparable to the data, despite there being a larger high-redshift tail. The post-Herschel Bethermin et al (2010c) model closely agrees with the observed evolution in both COSMOS and GOODS (Fig. 7).…”

“…The model of Bethermin et al (2010c) provides a close fit to our data in the low, intermediate, and high redshift ranges, most likely because it is based on a optimal minimization between the model and the most recent Spitzer and Herschel data, and already takes into account the FIR and submm statistical properties of galaxies (see Sect. 4.5).…”

“…Using only the post-Herschel model in hand (Bethermin et al 2010c), our data indicate that we can resolve in COSMOS data 90% at 160 μm and 98% at 70 μm of the background we should detect by applying the selection at 24 μm. Our selection introduces an incompleteness in the CIB estimate corresponding to the fainter 24 μm sources (S 24 < 80 μJy), omitted from our analysis; this omission implies that we resolve 68% of the total 160 μm background and 81% of the total 70 μm background in COSMOS (see Sect.…”

“…Lagache et al 2005;Bethermin et al 2010c). The 24 μm background contains, however, a significant contribution from galaxies at z > 1 (30%, according to Le Floc'h et al 2009).…”

Dusty star-forming galaxies at high redshift

“…In contrast, earlier predictive work by Lagache et al (2005) addresses the overall redshift distribution for the underlying 350µm population, which peaks at substantially lower redshift, z ≈ 1, with a long tail out to high redshifts. Another phenomenological approach described in Béthermin et al (2011), working backwards from constrained luminosity functions to redshift distributions and number counts predicts a peak at very low redshifts with a secondary peak 10 at z ∼ 2. Béthermin et al (2012b) present yet another new approach which is strictly empirical using the observed evolution in the stellar mass function of star-forming galaxies and the observed infrared main sequence of galaxies Sargent et al, 2012); they use empirical templates from Magdis et al (2012b) as a function of main-sequence status to predict number counts and also source redshift distributions.…”