Luminosity functions of local infrared galaxies with AKARI: implications for the cosmic star formation history and AGN evolution

Author： Goto Tomotsugu Arnouts Stephane Inami Hanae Matsuhara Hideo Pearson Chris Takeuchi Tsutomu T. Le Floc'h Emeric Takagi Toshinobu Wada Takehiko Nakagawa Takao Oyabu Shinki Ishihara Daisuke Mok Lee Hyung Jeong Woong-Seob Yamauchi Chisato Serjeant Stephen Sedgwick Chris Treister Ezequiel

Publisher： Oxford University Press

ISSN： 0035-8711

Source： Monthly Notices of the Royal Astronomical Society, Vol.410, Iss.1, 2011-01, pp. : 573-584

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Abstract

ABSTRACTInfrared (IR) luminosity is fundamental to understanding the cosmic star formation history and active galactic nuclei (AGN) evolution, since their most intense stages are often obscured by dust. However, local IR luminosity function estimates today are still based on the IRAS survey in the 1980s, with wavelength coverage only up to 100 μm. The AKARI IR space telescope performed an all-sky survey in six IR bands (9, 18, 65, 90, 140 and 160 μm ) with 3–10 times better sensitivity, covering the crucial far-IR wavelengths across the peak of the dust emission. Combined with a better spatial resolution, AKARI can much more precisely measure the total infrared luminosity (L_TIR) of individual galaxies, and thus, the total infrared luminosity density in the local Universe.By fitting modern IR spectral energy distribution (SED) models, we have remeasured L_TIR of the IRAS Revised Bright Galaxy Sample, which is a complete sample of local galaxies with S_{60 μm} > 5.24 Jy.We present mid-IR monochromatic luminosity (νL_ν) to L_TIR correlations for Spitzer 8 μ m, AKARI 9 μ m, IRAS 12 μ m, WISE 12 μ m, ISO 15 μ m, AKARI 18 μ m, WISE 22 μ m and Spitzer 24 μ m filters. These measures of L_MIR are well correlated with L_TIR , with scatter in the range 13–44 per cent. The best-fitting L_MIR -to- L_TIR conversions provide us with estimates of L_TIR using only a single MIR band, in which several deep all-sky surveys are becoming available such as AKARI MIR and WISE.Although we have found some overestimates of L_TIR by IRAS due to contaminating cirrus/sources, the resulting AKARI IR luminosity function (LF) agrees well with that from IRAS. We integrate the LF weighted by L_TIR to obtain a cosmic IR luminosity density of Ω_TIR= (8.5^+1.5_−2.3) × 10⁷ L_⊙ Mpc⁻³, of which 7 ± 1 per cent is produced by luminous infrared galaxies (LIRGs) (L_TIR > 10¹¹ L_⊙) , and only 0.4 ± 0.1 per cent is from ultraluminous infrared galaxies (ULIRGs) (L_TIR > 10¹² L_⊙) in the local Universe, in stark contrast to high-redshift results.We separate the contributions from AGN and star-forming galaxies (SFGs). The SFG IR LF shows a steep decline at the bright end. Combined with high-redshift results from the AKARI NEP deep survey, these data show a strong evolution of Ω^SF_TIR∝ (1 +z) ^4.0±0.5 and Ω^AGN_TIR∝ (1 +z) ^4.4±0.4 . For Ω^AGN_TIR , the ULIRG contribution exceeds that from LIRGs already by z∼ 1 . A rapid evolution in both Ω^AGN_TIR and Ω^SFG_TIR suggests the correlation between star formation and black hole accretion rate continues up to higher redshifts. We compare the evolution of Ω^AGN_TIR to that of X-ray luminosity density. The Ω^AGN_TIR/Ω_X-ray^AGN ratio shows a possible increase at z > 1 , suggesting an increase of obscured AGN at z > 1 .