Cosmic star formation history revealed by the AKARI, & Spatially-resolved spectroscopy of an E+A (Post-starburst) system

TL;DR

This study uses deep infrared observations from AKARI to map the cosmic star formation history, revealing strong evolution in infrared luminosity functions and the increasing importance of luminous infrared galaxies at higher redshifts.

Contribution

It provides the first continuous mid-IR coverage to accurately estimate luminosity functions and cosmic infrared luminosity density evolution up to z~2.

Findings

Infrared luminosity functions show strong evolution with redshift.

Cosmic infrared luminosity density scales as (1+z)^4.4.

LIRGs and ULIRGs become more dominant at higher redshifts.

Abstract

We reveal cosmic star-formation history obscured by dust using deep infrared observation with the AKARI. A continuous filter coverage in the mid-IR wavelength (2.4, 3.2, 4.1, 7, 9, 11, 15, 18, and 24um) by the AKARI satellite allows us to estimate restframe 8um and 12um luminosities without using a large extrapolation based on a SED fit, which was the largest uncertainty in previous work. We found that restframe 8um (0.38<z<2.2), 12um (0.15<z<1.16), and total infrared (TIR) luminosity functions (LFs) (0.2<z<1.6) constructed from the AKARI NEP deep data, show a continuous and strong evolution toward higher redshift. In terms of cosmic infrared luminosity density (Omega_IR), which was obtained by integrating analytic fits to the LFs, we found a good agreement with previous work at z<1.2, with Omega_IR propto (1+z)^4.4+-1.0. When we separate contributions to Omega_IR by LIRGs and ULIRGs, we found more IR luminous sources are increasingly more important at higher redshift. We found that the ULIRG (LIRG) contribution increases by a factor of 10 (1.8) from z=0.35 to z=1.4.