Detection of CFIRB with AKARI/FIS Deep Observations

TL;DR

This paper assesses AKARI/FIS deep observations' capability to detect the Cosmic Far-Infrared Background (CFIRB) fluctuations, considering confusion limits, to understand galaxy evolution.

Contribution

It provides a comprehensive analysis of confusion noise and observational strategies for detecting CFIRB with AKARI/FIS under various galaxy evolution models.

Findings

Detection of CFIRB fluctuations is feasible in low-to-medium cirrus regions.

Source confusion limits observations more than instrumental noise.

CFIRB measurements can distinguish galaxy evolution scenarios.

Abstract

The Cosmic Far-Infrared Background (CFIRB) contains information about the number and distribution of contributing sources and thus gives us an important key to understand the evolution of galaxies. Using a confusion study to set a fundamental limit to the observations, we investigate the potential to explore the CFIRB with AKARI/FIS deep observations. The Far-Infrared Surveyor (FIS) is one of the focal-plane instruments on the AKARI (formerly known as ASTRO-F) satellite, which was launched in early 2006. Based upon source distribution models assuming three different cosmological evolutionary scenarios (no evolution, weak evolution, and strong evolution), an extensive model for diffuse emission from infrared cirrus, and instrumental noise estimates, we present a comprehensive analysis for the determination of the confusion levels for deep far-infrared observations. We use our derived sensitivities to suggest the best observational strategy for the AKARI/FIS mission to detect the CFIRB fluctuations. If the source distribution follows the evolutionary models, observations will be mostly limited by source confusion. We find that we will be able to detect the CFIRB fluctuations and that these will in turn provide information to discriminate between the evolutionary scenarios of galaxies in most low-to-medium cirrus regions.