Evolution of mid-infrared galaxy luminosity functions from the entireAKARINEP deep field with new CFHT photometry

Abstract

We present infrared galaxy luminosity functions (LFs) in the AKARI North Ecliptic Pole (NEP) deep field using recently-obtained, wider CFHT optical/near-IR images. AKARI has obtained deep images in the mid-infrared (IR), covering 0.6 deg 2 of the NEP deep field. However, our previous work was limited to the central area of 0.25 deg 2 due to the lack of optical coverage of the full AKARI NEP survey. To rectify the situation, we recently obtained CFHT optical and near-IR images over the entire AKARI NEP deep field. These new CFHT images are used to derive accurate photometric redshifts, allowing us to fully exploit the whole AKARI NEP deep field.AKARI's deep, continuous filter coverage in the mid-IR wavelengths (2.4, 3.2, 4.1, 7, 9, 11, 15, 18, and 24µm) exists nowhere else, due to filter gaps of other space telescopes. It allows us to estimate restframe 8µm and 12µm luminosities without using a large extrapolation based on spectral energy distribution (SED) fitting, which was the largest uncertainty in previous studies. Total infrared luminosity (TIR) is also obtained more reliably due to the superior filter coverage. The resulting restframe 8µm, 12µm, and TIR LFs at 0.15 < z < 2.2 are consistent with previous works, but with reduced uncertainties, especially at the high luminosity-end, thanks to the wide field coverage. In terms of cosmic infrared luminosity density (Ω IR ), we found that the Ω IR evolves as ∝ (1 + z) 4.2±0.4 .

Evolution of Cosmic Molecular Gas Mass Density from z ∼ 0 to z = 1–1.5

“…In Figure 2, the best-fit CSFRD evolution by Madau & Dickinson (2014) is also plotted, which has an uncertainty of about 0.2 dex as seen in their Figure 9. The CSFRD increases about ten times from z ∼ 0 to z ∼ 1.5 (contribution from ULIRGs at z = 1 − 1.5 is not large (10 − 40%) (Casey et al 2012;Goto et al 2015). Our results show the CMGD is also about ten times larger at z ∼ 1.4 than at z ∼ 0.…”

An Empirical Determination of the Intergalactic Background Light From Uv to Fir Wavelengths Using Fir Deep Galaxy Surveys and the Gamma-Ray Opacity of the Universe

“…This method can be used in conjunction with future deep galaxy survey observations using the near infrared and mid-infrared instruments aboard the James Webb Space Telescope. AKARI 8 and 12 µm data are from Goto et al (2015), Spitzer data at 8 µm are from Huang et al (2007) and Caputi et al (2007). Spitzer data at 8 and 24 µm are from Babbedge et al (2006).…”

“…Rodighiero et al (2010). AKARI 8 and 12 μm data are from Goto et al (2015), and Spitzer data at 8 μm are from Huang et al (2007) and Caputi et al (2007). Spitzer data at 8 and 24 μm are from Babbedge et al (2006).…”

Far-infrared dust properties of highly dust-obscured active galactic nuclei from the AKARI and WISE all-sky surveys

“…This is especially true for particularly luminous AGNs, in which most of the mid-IR PAH features are absent due to photodisassociation by the AGN emission. Even with WISE photometry, the width of the W 1 and W 2 bands and large gaps between the W 2, W 3, and W 4 bands do not allow emission features to be easily visible (in contrast, Goto et al (2015) exploits AKARI's near-continuous filter coverage in the mid-IR for z photo measurements in AKARI NEP field). Although it is possible to use the photometry that we have to estimate photometric redshifts using codes such EAZY (Brammer et al 2008) or LEPHARE (Arnouts et al 1999;Ilbert et al 2006), the strong AGN power-law behavior makes it extremely difficult to reliably estimate photometric redshifts for these objects without additional photometry.…”