Mid-Infrared Luminosity Function of Local Star-Forming Galaxies in the NEP-Wide Survey Field of AKARI

TL;DR

This study derives accurate mid-infrared luminosity functions for local star-forming galaxies using spectroscopic data from the AKARI NEP-Wide Survey, revealing luminosity evolution over cosmic time.

Contribution

It provides the first MIR luminosity functions based on spectroscopic redshifts in the NEP-Wide field, improving accuracy over previous photometric studies.

Findings

MIR luminosity functions are consistent with previous studies across different fields.

The 8 micron LF fits a double power-law with specific indices.

Results indicate luminosity evolution from higher redshifts to the present.

Abstract

We present mid-infrared (MIR) luminosity functions (LFs) of local star-forming (SF) galaxies in the AKARI NEP-Wide Survey field. In order to derive more accurate luminosity function, we used spectroscopic sample only. Based on the NEP-Wide point source catalogue containing a large number of infrared (IR) sources distributed over the wide (5.4 sq. deg.) field, we incorporated the spectroscopic redshift data for about 1790 selected targets obtained by optical follow-up surveys with MMT/Hectospec and WIYN/Hydra. The AKARI continuous 2 to 24 micron wavelength coverage as well as photometric data from optical u band to NIR H-band with the spectroscopic redshifts for our sample galaxies enable us to derive accurate spectral energy distributions (SEDs) in the mid-infrared. We carried out SED fit analysis and employed 1/Vmax method to derive the MIR (8, 12, and 15 micron rest-frame) luminosity functions. We fit our 8 micron LFs to the double power-law with the power index of alpha= 1.53 and beta= 2.85 at the break luminosity. We made extensive comparisons with various MIR LFs from several literatures. Our results for local galaxies from the NEP region are generally consistent with other works for different fields over wide luminosity ranges. The comparisons with the results from the NEP-Deep data as well as other LFs imply the luminosity evolution from higher redshifts towards the present epoch.