2011MNRAS.414.1903G

By cross-correlating the AKARI all-sky survey in six infrared (IR) bands (9, 18, 65, 90, 140 and 160 µm) with the Sloan Digital Sky Survey (SDSS) galaxies, we identified 2357 IR galaxies with a spectroscopic redshift. This is not just one of the largest samples of local IR galaxies, but AKARI provides crucial far-IR (FIR) bands for accurately measuring the galaxy spectral energy distribution (SED) across the peak of the dust emission at > 100 µ m. By fitting modern IR SED models to the AKARI photometry, we measured the total infrared luminosity (L_IR) of individual galaxies.

Using this L_IR, we constructed the luminosity functions (LF) of IR galaxies at a median redshift of z= 0.031. The LF agrees well with that at z= 0.0082 (the Revised Bright Galaxy Sample), showing smooth and continuous evolution towards higher redshift LFs measured in the AKARI North Ecliptic Pole (NEP) deep field. By integrating the IR LF weighted by L_IR, we measured the local cosmic IR luminosity density of Ω_IR= (3.8^+5.8_–1.2) {x} 10⁸ L_☉/Mpc3. We separate galaxies into active galactic nuclei (AGN), star-forming galaxies (SFG) and composite by using the [N II]/Hα versus [O III]/Hβ line ratios. The fraction of AGN shows a continuous increase with increasing L_IR from 25 to 90 per cent at 9 < log L_IR< 12.5. The SFR_Hα and L_[OIII] show good correlations with L_IR for SFG and AGN, respectively. The self-absorption-corrected Hα/Hβ ratio shows a weak increase with L_IR with a substantial scatter. When we separate IR LFs into contributions from AGN and SFG, the AGN contribution becomes dominant at L_IR> 10¹¹ L_☉, coinciding with the break of both the SFG and AGN IR LFs. At L_IR ≤ 10¹¹ L_☉, SFG dominates IR LFs. Only 1.1±0.1 per cent of Ω_IR is produced by luminous infrared galaxies (L_IR> 10¹¹ L_☉), and only 0.03±0.01 per cent by ultraluminous infrared galaxies (L_IR> 10¹² L_☉) in the local Universe. Compared with high-redshift results from the AKARI NEP deep survey, we observed a strong evolution of Ω^SFG_IR∝ (1 +z)^4.1±0.4 and Ω^AGN_IR∝ (1 +z)^4.1±0.5. Our results show that all of our measured quantities (IR LFs, L*, Ω^AGN_IR, Ω^SFG_IR) show smooth and steady increase from lower redshift (the Revised Bright Galaxy Sample) to higher redshift (the AKARI NEP deep survey).