あかりの中間赤外-遠赤外観測に基づく 系内における多環式芳香族炭化水素と古典ダストの放射

Itsuki Sakon, Takashi Onaka, Yasuo Doi(University of Tokyo) Hidehiro Kaneda, Daisuke Ishihara(Nagoya University),

Yoko Okada(University of Cologne), AKARI team Michael W. Werner (NASA, JPL), Thomas L. Roellig (NASA, Ames)

UIR Bands and PAHs

trio duo quartet

solo

UV photon

ener

gy UV

photon

IR photons

H C C

C C C C

CH out-of-plane bending CH in-plane

bending

CH stretching

CC stretching

UIR bands • 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)

Polycyclic Aromatic Hydrocarbons (PAHs) (Allamandola et al. 1989)

IV II I III

I II

IV III

Solar circle

Area I : -12o≦l≦-4o

Area II : 48o≦l≦52o

Area III:-136o≦l≦-128o

Area IV : 168o≦l≦176o

Inner Galactic Plane

Outer Galactic Plane

Observation; IRTS/Mid-Infrared Spectrometer (MIRS) 4.5µm ~ 11.8µm with spectral resolution 0.225µm

Mid-Infrared Spectroscopy of diffuse Galactic emission with Infrared Telescope in Space (IRTS)

Observed areas on the Galactic plane (|b|<4o) Map quoted from Georgelin & Gerogelin (1976)

We

UIR 7.7μm band intensity map for Area I, Area II, Area III, Area IV

Area I Area IV Area III Area II

The IRTS/MIRS spectra of Areas I--IV

UIR 7.7µm band intensity maps of Areas I--IV

Higher UIR band ratios of 6.2µm/11.2µm, 7.7µm/11.2µm in the inner Galactic plane than in the outer Galactic plane are suggested (Sakon et al. 2004, ApJ, 609, 203)

Mid-Infrared Spectroscopy of diffuse Galactic emission with Infrared Camera (IRC) onboard AKARI

Solar circle (DG=8.5kpc)

Map quoted from Georgelin & Gerogelin (1976)

CAR-79

CAR-57

CRU-48

CAR+32

CAR+70

CAR+109 Observation; AKARI/IRC Mission Program; ISMGN (PI. H. Kaneda) Slit Spectroscopy with an AOT “IRC04” (slit size; 5” x 40”) Near-Infrared; NP (2µm-5.5µm) Mid-Infrared; SG1 (5µm—7.8µm) SG2 (7.6µm—13µm) A List of Obtained Datasets Area ID. l (o) Arm ID. Pointings CAR-79 -79o Carina 5 CAR-57 -57o Carina 4 CRU-48 -48o Carina + Crux 5 CRU+32 +32o Carina + Crux 3 PER+70 +70o Perseus 4 PER+109 +109o Perseus 1

Data

Solar circle (DG=8.5kpc)

Map quoted from Georgelin & Gerogelin (1976)

CAR-79

CAR-57

CRU-48

CAR+32

CAR+70

CAR+109

Slit Positions in the Inner Galactic Plane Pointing ID. Area ID. ( l , b) [deg] 1400225.1 CAR-057 -54.5, -0.5 1400229.1 CAR-057 -54.5, 0.0 1400215.1 CAR-057 -53.5, 0.0 1400247.1 CRU-048 -48.0, -0.5 1400251.1 CRU-048 -47.5, -0.5 1400257.1 CRU-048 -48.5, -0.0 1400259.1 CRU-048 -48.5, 0.5 1400261.1 CRU-048 -48.0, 0.5 1401033.1 CRU+032 35.4, -1.0 1401027.1 CRU+032 32.4, 0.5

Slit Positions in the Outer Galactic Plane Pointing ID. Area ID. ( l , b) [deg] 1402304.1 CAR-079 -80.0, -1.5 1400197.1 CAR-079 -79.0, -1.0 1400201.1 CAR-079 -80.0, -1.0 1402301.1 CAR-079 -78.5, -1.0 1400203.1 CAR-079 -80.0, -0.5 1402370.1 PER+070 71.0, -1.0 1402369.1 PER+070 71.5, -1.0 1401017.1 PER+070 70.5, -0.5 1402365.1 PER+070 71.5, -0.4 1402389.1 PER+109 108.4, 0.5

Slit Positions in the Off-Plane Pointing ID. Area ID. ( l , b) [deg] 1400231.1 CAR-057 -54.0, -2.5

AKARI/IRC Mid-Infrared Spectra of Diffuse Galactic Emission in the inner Galactic Plane

l~+32deg, |b| <1.5 l~-57deg, |b| <1.5

AKARI/IRC Mid-Infrared Spectra of Diffuse Galactic Emission in the inner Galactic Plane

l~-48deg, |b| <1.5

AKARI/IRC Mid-Infrared Spectra of Diffuse Galactic Emission in the outer Galactic Plane

l~70deg, |b| <1.5 l~109deg, |b| <1.5

AKARI/IRC Mid-Infrared Spectra of Diffuse Galactic Emission in the outer Galactic Plane

l~-79deg, |b| <1.5

AKARI/IRC Mid-Infrared Spectra of Diffuse Galactic Emission in the Off-Plane

l~-57deg, |b| <1.5 l~-57deg, |b| ~2.5

Inner Galactic Plane Direction ID IUIR6.2 IUIR7.7 IUIR8.6 IUIR11.2 Tdust τ100µm I60µm/I100µm UIR6.2/UIR11.2 UIR7.7/UIR11.2 UIR8.6/UIR11.2 [×10-18Wcm-2pix-1] (no extinction correction) [K] (corrected for extinction) CRU+32 1401033 5.7(0.2) 16.0(0.3) 1.6(0.2) 4.8(0.2) 17.90 0.0629 0.347 1.21(0.07) 3.26(0.17) 0.34(0.05) CRU+32 1401027 8.3(0.2) 22.5(0.3) 2.9(0.2) 7.3(0.2) 17.25 0.0348 0.292 1.15(0.05) 3.06(0.11) 0.42(0.04) CRU-48 1400247 8.3(0.2) 20.3(0.3) 2.4(0.2) 6.4(0.2) 17.01 0.1175 0.272 1.33(0.06) 3.08(0.12) 0.41(0.04) CRU-48 1400251 8.6(0.2) 21.3(0.3) 2.4(0.2) 6.7(0.2) 17.10 0.1097 0.280 1.31(0.05) 3.09(0.11) 0.39(0.04) CRU-48 1400257 13.7(0.2) 34.5(0.3) 4.0(0.2) 9.2(0.2) 17.24 0.1874 0.291 1.56(0.05) 3.62(0.10) 0.50(0.03) CRU-48 1400259 18.4(0.2) 44.6(0.3) 4.2(0.2) 10.1(0.2) 18.52 0.0526 0.400 1.85(0.05) 4.37(0.10) 0.44(0.03) CRU-48 1400261 12.8(0.2) 32.3(0.3) 3.9(0.2) 8.9(0.2) 17.11 0.0577 0.280 1.45(0.04) 3.56(0.10) 0.46(0.03) CAR-57 1400225 7.2(0.2) 17.7(0.3) 2.7(0.2) 5.3(0.2) 18.27 0.0610 0.379 1.38(0.07) 3.30(0.15) 0.54(0.05) CAR-57 1400229 11.8(0.2) 28.0(0.3) 1.6(0.2) 7.4(0.2) 23.28 0.0441 0.804 1.61(0.06) 3.72(0.12) 0.22(0.03) CAR-57 1400215 10.2(0.2) 22.1(0.3) 3.0(0.2) 6.4(0.2) 17.31 0.0932 0.297 1.64(0.07) 3.40(0.13) 0.51(0.04)

Outer Galactic Plane Direction ID IUIR6.2 IUIR7.7 IUIR8.6 IUIR11.2 Tdust τ100µm I60µm/I100µm UIR6.2/UIR11.2 UIR7.7/UIR11.2 UIR8.6/UIR11.2 [×10-18Wcm-2pix-1] (no extinction correction) [K] (corrected for extinction) PER+70 1402370 1.7(0.2) 4.9(0.3) 0.8(0.2) 1.6(0.2) 17.27 0.0114 0.294 1.06(0.20) 3.02(0.47) 0.52(0.16) PER+70 1402369 2.1(0.2) 5.0(0.3) 0.7(0.2) 1.6(0.2) 17.22 0.0122 0.290 1.37(0.24) 3.20(0.51) 0.42(0.16) PER+70 1401017 3.0(0.2) 6.4(0.3) 1.0(0.2) 2.3(0.2) 16.81 0.0187 0.255 1.28(0.15) 2.73(0.30) 0.43(0.11) PER+70 1402365 15.3(0.2) 37.6(0.3) 3.3(0.2) 9.4(0.2) 21.69 0.0046 0.669 1.63(0.05) 4.01(0.10) 0.36(0.03) CAR-79 1402304 2.0(0.2) 4.6(0.3) 0.8(0.2) 2.1(0.2) 16.83 0.0109 0.257 0.97(0.15) 2.22(0.29) 0.41(0.12) CAR-79 1400197 3.0(0.2) 6.7(0.3) 1.0(0.2) 2.4(0.2) 17.16 0.0148 0.285 1.26(0.15) 2.76(0.29) 0.42(0.11) CAR-79 1400201 1.6(0.2) 3.6(0.3) 0.6(0.2) 1.7(0.2) 16.97 0.0096 0.269 0.97(0.18) 2.15(0.35) 0.39(0.15) CAR-79 1402301 3.6(0.2) 8.8(0.3) 1.2(0.2) 3.3(0.2) 18.29 0.0155 0.380 1.10(0.10) 2.64(0.21) 0.36(0.08) CAR-79 1400203 1.7(0.2) 3.7(0.3) 0.7(0.2) 1.7(0.2) 18.77 0.0041 0.421 1.02(0.18) 2.15(0.34) 0.41(0.15) PER+109 1402389 2.3(0.2) 5.3(0.3) 0.7(0.2) 2.1(0.2) 16.97 0.0123 0.269 1.12(0.16) 2.54(0.32) 0.35(0.12)

Off-Plane Direction ID IUIR6.2 IUIR7.7 IUIR8.6 IUIR11.2 Tdust τ100µm Iν60µm/Iν100µm UIR6.2/UIR11.2 UIR7.7/UIR11.2 UIR8.6/UIR11.2 [×10-18Wcm-2pix-1] (no extinction correction) [K] (corrected for extinction) CAR-57 1400231 0.8(0.2) 2.7(0.3) 0.4(0.2) 0.9(0.2) 17.31 0.0092 0.297 0.87(0.31) 2.87(0.79) 0.45(0.28)

Mid-Infrared Properties of PAHs in diffuse Galactic Emission

-- Tdust is calculated from the empirical relation of Tdust = 11.8 × (Iν60µm/Iν100µm) +13.8 (K) given by Nagata et al. (2002) -- Iν60µm/Iν100µm is calculated from the ISSA data calibrated with COBE/DIRBE ZSMA data (e.g., Sakon et al. 2004; Sakon et al. 2006). -- τ6.2µm=4.8τ100µm , τ7.7µm = 3.8τ100µm , τ8.6µm = 6.1τ100µm , τ11.2µm = 4.3τ100µm (Sakon et al. 2004) are assumed to obtain intrinsic UIR band ratios.

The strengths of UIR 6.2µm and 7.7µm relative to 11.2µm in the inner Galactic Plane are systematically larger

than those in the outer Galactic Plane and in the off-Plane even if the extinction is taken into account.

PAHs in the photo-dissociation region (PDRs) are expected to be positively charged

ionization of PAHs ∝ U/ne or U/ne T1/2

U; Incident radiation field strength ne; electron density T; gas temperature

Greater contributions of PDRs within a beam in the inner Galactic Plane

than in the outer Galactic Plane and/or in the off-Plane may be responsible for the observed variations in the UIR band ratios

Inner Galactic Plane Outer Galactic Plane Off-Plane UIR6.2/UIR11.2 1.5±0.3 1.1±0.3 0.9±0.3 UIR7.7/UIR11.2 3.5±0.5 2.6±0.5 2.9±0.8

Ionization of PAHs in diffuse Galactic Emission

AKARI/FIS All Sky Survey Data of Inner Galactic Plane (|l|<60o, |b|<2o.5) (Doi et al. 2009) Slit Positions in the Inner Galactic Plane

Pointing ID. Area ID. ( l , b) [deg] 1400225.1 CAR-057 -54.5, -0.5 1400229.1 CAR-057 -54.5, 0.0 1400215.1 CAR-057 -53.5, 0.0 1400247.1 CRU-048 -48.0, -0.5 1400251.1 CRU-048 -47.5, -0.5 1400257.1 CRU-048 -48.5, -0.0 1400259.1 CRU-048 -48.5, 0.5 1400261.1 CRU-048 -48.0, 0.5 1401033.1 CRU+032 35.4, -1.0 1401027.1 CRU+032 32.4, 0.5 Slit Positions in the Off-Plane Pointing ID. Area ID. ( l , b) [deg] 1400231.1 CAR-057 -54.0, -2.5

30 35

0 1

-1 -2

2

Galactic Longitude (deg)

305 310 315 Galactic Longitude (deg)

0

1

-1

-2

2

Gal

actic

Lat

itude

(deg

)

Gal

actic

Lat

itude

(deg

)

AKARI/FIS All Sky Survey Data of Outer Galactic Plane (|l|>60o, |b|<2o.5) (Doi et al. in prep; Ootsubo et al. in prep)

70

0

1

-1

-2

2

Galactic Longitude (deg) 280

Galactic Longitude (deg)

Gal

actic

Lat

itude

(deg

)

Slit Positions in the Outer Galactic Plane Pointing ID. Area ID. ( l , b) [deg] 1402304.1 CAR-079 -80.0, -1.5 1400197.1 CAR-079 -79.0, -1.0 1400201.1 CAR-079 -80.0, -1.0 1402301.1 CAR-079 -78.5, -1.0 1400203.1 CAR-079 -80.0, -0.5 1402370.1 PER+070 71.0, -1.0 1402369.1 PER+070 71.5, -1.0 1401017.1 PER+070 70.5, -0.5 1402365.1 PER+070 71.5, -0.4 1402389.1 PER+109 108.4, 0.5

0

1

-1

-2

2

Gal

actic

Lat

itude

(deg

)

110 Galactic Longitude (deg)

0

1

-1

-2

2

Gal

actic

Lat

itude

(deg

)

SED Model Fit to AKARI/FIS All Sky Survey data Diffuse Galactic Emission; contributed by multiple components in the line of sight

2 temperature components model; T1=18K (U~1), T2=60K (U~1000)

Interpretation for the variations in UIR band ratios

UIR 6.2/11.2 UIR 7.7/11.2

UIR 8.6/11.2 UIR 6.2/7.7

Off plane (|b|~2.5deg) Inner Galactic Plane (|l|<70deg)

Interpretation for the variations in UIR band ratios

UIR 6.2/11.2 UIR 7.7/11.2

UIR 8.6/11.2 UIR 6.2/7.7

Off plane (|b|~2.5deg) Inner Galactic Plane (|l|<70deg) Outer Galactic Plane (|l|>70deg)