Understanding of the fate of dust in nearby galaxies using AKARI far-infrared data

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For the present study, I used the data of the infrared astronomical satellite, AKARI, which were taken in the obervational programs, "the interstellar medium in our Galaxy and nearby galaxies," and "all-sky surveys". Improving the method to process AKARI far-infrared imaging data, I have elucidated the evolution of dust grains in various interstellar environments of nearby galaxies. Because AKARI covered all the sky with improved sensitivities, I derived information on properties of dust in various harsh environments, providing entirely new knowledge on the shattering and destruction of dust, and processing of polycyclic aromatic hydrocarbons (PAHs). In particular, I find that copious amounts of dust are flowing out of galaxies by galactic superwinds, enriching the intergalactic space with dust. I also reveal the presence of PAHs in elliptical galaxies with unusual spectral features, demonstrating importance of the material processing in the interstellar space.