A halo model approach to describe clustering and emission of the two main star forming galaxy populations for Cosmic Infrared Background studies

TL;DR

This paper develops a halo model to analyze the clustering and emission of two main star-forming galaxy populations contributing to the Cosmic Infrared Background, using Planck and Herschel data to constrain their properties.

Contribution

It introduces a physically-motivated halo model distinguishing galaxy populations and fits it to observational data to study their clustering and emission characteristics.

Findings

Herschel-SPIRE data effectively constrains both galaxy populations.

Planck data alone cannot disentangle the two populations.

An inconsistency exists between Planck and Herschel results.

Abstract

The Cosmic Infrared Background (CIB), traced by the emission from dusty star-forming galaxies, provides a crucial window into the phases of star formation throughout cosmic history. These galaxies, although challenging to detect individually at high redshifts due to their faintness, cumulatively contribute to the CIB which then becomes a powerful probe of galaxy formation, evolution and clustering. Here, we introduce a physically-motivated model for the CIB emission spanning a wide range of frequency and angular resolution, employing a halo model approach and distinguishing, within dark matter halos, between two main populations of star forming galaxies, i.e. normal late-type spiral and irregular galaxies and the progenitors of early-type galaxies. The emission from two galaxy populations maps into different regimes in frequency/resolution space, allowing us to constrain the clustering parameters of the model - $M_{\text{min}}$, the mass of a halo with 50% probability of having a central galaxy and $\alpha$, the power law index regulating the number of satellite galaxies - through a fit to Planck and Herschel-SPIRE CIB anisotropy measurements. We find that, while being able to place constraints on some of the clustering parameters, the Planck frequency and multipole coverage cannot effectively disentangle the contributions from the two galaxy populations. On the other side, the Herschel-SPIRE measurements separate out and constrain the clustering of both populations. Our work, though, highlights an inconsistency of the results between the two datasets, partially already reported in other literature and still not understood.