Clustering of Far-Infrared Galaxies in the AKARI All-Sky Survey

TL;DR

This study measures the angular clustering of far-infrared galaxies from the AKARI survey, revealing significant large-scale structure and hemisphere differences, providing initial insights into their spatial distribution.

Contribution

First measurement of the angular two-point correlation function for AKARI 90-micron extragalactic sources, establishing baseline clustering properties in the far-infrared.

Findings

Detected non-zero clustering signal up to 40 degrees

Clustering well fitted by a power law

Identified hemisphere differences likely due to calibration issues

Abstract

We present the first measurement of the angular two-point correlation function for AKARI 90-$\mu$m point sources, detected outside of the Milky Way plane and other regions characterized by high Galactic extinction, and categorized as extragalactic sources according to our far-infrared-color based criterion (Pollo et al. 2010). This is the first measurement of the large-scale angular clustering of galaxies selected in the far-infrared after IRAS measurements. Although a full description of clustering properties of these galaxies will be obtained by more detailed studies, using either spatial correlation function, or better information about properties and at least photometric redshifts of these galaxies, the angular correlation function remains the first diagnostics to establish the clustering properties of the catalog and observed galaxy population. We find a non-zero clustering signal in both hemispheres extending up to $\sim 40$ degrees, without any significant fluctuations at larger scales. The observed correlation function is well fitted by a power law function. The notable differences between a northern and southern hemisphere are found, which can be probably attributed to the photometry problems and point out to a necessity of performing a better calibration in the data from southern hemisphere.