Seong-Jin KIM (National Tsing Hua University), Tomotsugu GOTO (National Tsing Hua University), Matt Malkan (Department of physics and astronomy, UCLA), and the NEP team
Polycyclic aromatic hydrocarbons (PAHs) are out in space, essentially everywhere in the interstellar medium (ISM), near our Galaxy as well as others far away. However, we do not know their exact structures or origins. Their complexity of the spectra makes the actual interpretation difficult. The infrared space telescopes have been trying to reveal clues to these puzzles. For example, the Spitzer telescope gave large contributions to the PAH astrophysics with high sensitivity, but the MIR range, where we can observe a series of strong emission features (at 3.3, 6.2, 7.7, 8.6, 11.3, 12.7 μm), has not been fully observed. Thereby, it is still hard to clear out their mysterious connections to galaxy evolution or star-forming activities. We have valuable data continuously covering this MIR range, through the legacy NEP survey of the AKARI space telescope (which took advantage of the unique filter bands covering these wavelengths). However, this data set has not been fully available owing to the serious lack of photometric redshifts because of the shallow depths or incomplete coverage of the optical data. Now, with the recently reduced HSC data on this field and the newly released source catalogue with photometric redshift information, more detailed analyses are possible, especially based on the physically motivated modelling using the mixture of various star formation scenario, AGN, and ISM (e.g., dust) models. We will discuss the recent analysis at the conference.