AKARI MP/ISMGN team, AKARI IRC team

Very Small Grains (graphites, small silicate ) (VSGs; 1~10nm, stochastic heating)Interstellar dust(carbonaceous, silicate, etc.) PAH platelet ()PAH cluster ()Amorphous carbonCarbonaceous DustPAH moleculeComposition Polycyclic Aromatic Hydrocarbons (PAHs; ~10) Submicron dust (in thermal equilibrium) (BGs; ~100nm) Infrared emission from diffuse ISM

IRAS 12/25 and young star clusters (

ISRF distribution; f(U)U-b for Umin < U < Umax U=1 corresponds to solar vicinity value (Mathis, Mezger, and Panagia 1983) Around the Young Star Clusters ; ( Umin , Umax ) = (1, 105) Regions without Young Star Clusters; ( Umin , Umax ) = (0.5, 102) (cf. Sakon et al. 2004, 2006,Tokura et al. 2006, Hibi et al. 2006)SED characteristics of dust emission around young star clusters in the LMC

SED characteristics of dust emissionin the CO Molecular Clouds in the LMCCO Molecular Clouds; NANTEN 12CO(J=1->0) LMC survey data at l=2.7mm (Fukui 2002; Yamaguchi et al. 2001; Mizuno et al. 2001) HPBW 2.6 at 115GHz Infrared SED; IRAS Sky Survey Atlas 12mm, 25mm, 60mm, 100mm beam size ; 4 x 4 -> only the data more than 16 apart from the young (

SED characteristics of dust emissionin the CO Molecular Clouds in the LMCISRF distribution; f(U)U-b for Umin < U < Umax b ; CO I12CO

b ; CO I12CO Umin ; CO Umin~0.1; TBGs~13K (Miville-Deschenes et al. 2002)Umax ; CO IRAS 12mm / 25mm vs. b for various (Umin , Umax ) (Umin , Umax ) = (0.1, 10) ; Arc I, Molecular Ridge South etc. (Umin , Umax ) = (0.1, 1000) ; Arc III, Molecular Ridge North etc.(Sakon et al. 2006)

Unidentified Infrared BandsUbiquitous presence of UIR emission HII region, Reflection Nebulae, Planetary Nebulae, etc. (Tokunaga et al. 1997) Diffuse ISM (Onaka et al. 1996; Mattila et al. 1996)

External Galaxies (e.g. Helou et al. 2000) even at z~2 (Yan et al. 2004)

Focal plane of AKARI/IRC channels(Onaka et al. 2007)

System spectral response curves of AKARI/IRC imaging filters

SG1 : UIR 6.2mm, 7.7mm SG2 : UIR 8.6mm, 11.2mm NP/NG: UIR 3.3mm(Ohyama et al. 2007)System spectral response curves of AKARI/IRC spectroscopic filters

AKARI/IRC spectroscopy of Diffuse ISM in the LMCIRAS 12mm/25mmMolecular Cloud with Young star cluster near N159Molecular Cloud without young star clusters

AKARI/IRC spectroscopy of Diffuse ISM in the LMCMolecular Cloud with Young star cluster (, ) : small 12mm/25mm, large UIR 7.7/11.2Molecular Cloud without Young star cluster () : large 12mm/25mm, small UIR 7.7/11.2 [ArIII][SIV][NeII][ArIII][SIV][NeII]UIR6.2UIR7.7UIR8.6UIR11.2UIR12.7Molecular Cloud with Young star cluster near N159Molecular Cloud without young star clusters

AKARI/IRC Slit-spectroscopy of diffuse ISM in NGC6946

UIR bands in NGC6946Band strengths of UIR 6.2mm and 7.7mm features relative to that of UIR 11.2mm feature become stronger in the arm region than in the inter-arm region :IRC MIR-S/SG1 & SG2 spectra: Arm region, Inter-arm region Zodiacal emission is not subtracted as for (a) and (b)UIR 11.2mmUIR 6.2, 7.7mmUIR 11.2mmUIR 6.2, 7.7mmUIR 11.2mmUIR 6.2, 7.7mminter-armarmstar forming region

Properties of PAHs in NGC6946UIR band ratios of 6.2mm/11.2mm, 7.7mm/11.2mm, 8.6mm/11.2mm UIR band ratio Inter-Arm*1 Arm*2 S.F.Region*2

[6.2 / 11.2] ext.corr. 0.84(0.14) 1.33(0.13) 2.36(0.64)

[7.7 / 11.2] ext.corr. 2.27(0.32) 3.32(0.35) 5.51(1.44)

[8.6 / 11.2] ext.corr. 0.50(0.14) 0.56(0.09) 0.66(0.28)

*1 no extinction correction for the extreme case*2 Taking account of the extinction of Av=3 mag (Ferguson, Gallagher & Wyse 1998).- As a valid measure of the on-going star formation gas-phase PAHs (20 - 100 NC) / PAH clusters (~500NC) Feature Inter-Arm Arm S.F.Region

UIR* / plateau 0.60(0.018) 0.65(0.009) 0.70(0.016)

* Total intensity of UIR 6.2mm + 7.7mm + 8.6mm featuresUIR band / plateau emission in7-9mm More abundant small sized (free-flying) PAHs in Star forming Region possibly as a result of photo-evaporation of PAH clusters into free-flying PAHsUIR band / Plateau Emission in7-9mmcf. second plateau component in Peeters et al.2002

PAHs and PAH clusters(Rapacioli, Joblin and Boissel 2005, A&A, 429, 193)A : ionized PAHs large 7.57mmB : neutral PAHs small 7.63mm C : PAH clusters -- 7.85mm UIR7.7/11.2Peak position of 7.7mm complexABC-> 7.6mm / 7.8mm ratios: PAHs/PAH clusters

PAHs and PAH clustersResults of the fit 7.6mm component 7.8mm component ratio lcenter(fixed) h7.6(free) D7.6(free) lcenter(fixed) h7.8(free) D7.8(free) I(7.6) / I(7.8) (mm) (W/m2/um/pixel) (mm) (mm) (W/m2/um/pixel) (mm) Arm region 7.60 1.34E-16 0.16 7.83 1.40E-16 0.29 0.53Inter-arm region 7.60 5.84E-17 0.16 7.83 6.95E-17 0.36 0.37

-> More abundant small sized (free-flying) PAHs in Star forming Region as a result of photo-evaporation of PAH clusters into free-flying PAHsLarger ratio of I(7.6)/I(7.8) in star forming region