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Image Stacking Analysis of SDSS Galaxies with AKARI Far-Infrared Surveyor Maps at 65μm, 90μm, and 140μm

We perform image stacking analysis of Sloan Digital Sky Survey (SDSS) photometric galaxies over the AKARI Far-Infrared Surveyor (FIS) maps at 65μm, 90μm, and 140μm. The resulting image profiles are decomposed into the central galaxy component (single term) and the nearby galaxy component (clustering term), as a function of the r-band magnitude, m_r of the central galaxy. We find that the mean far-infrared (FIR) flux of a galaxy with magnitude m_r is well fitted with f^s_{90μm}=13*10^{0.306(18-m_r)}[mJy]. The FIR amplitude of the clustering term is consistent with that expected from the angular-correlation function of the SDSS galaxies, but galaxy morphology dependence needs to be taken into account for a more quantitative conclusion. We also fit the spectral energy distribution of stacked galaxies at 65μm, 90μm, and 140μm, and derive a mean dust temperature of ~30K. This is consistent with the typical dust temperature of galaxies that are FIR luminous and individually detected.