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I. Origin of the dust emission from Tycho’s SNR II. Mapping observations of [Fe II] lines and dust emission of IC443 by IRSF & AKARI III. Summary AKARI infrared observations of SNRs Ishihara Daisuke (Nagoya Univ.)
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I. Origin of the dust emission from Tycho’s SNR Ishihara, D., et al. 2010
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- Observed in 1572 by Tycho Brahe - Type Ia - Distance = 1.5 ~ 3.1 kpc - Detection of IR emissioin + IRAS (Schwaltz 1995) + ISO/ISOCAM (Douvion+ 2001) - Size = 8’ (5.3pc) - Extensively studied in X-ray, Radio and Optical Tycho’s SNR - Observed in 1572 by Tycho Brahe - Type Ia - Distance = 1.5 ~ 3.1 kpc - Detection of IR emissioin + IRAS (Schwaltz 1995) + ISO/ISOCAM (Douvion+ 2001) - Size = 8’ (5.3pc) - Extensively studied in X-ray, Radio and Optical Tycho’s SNR 1. Tycho’s SNR - introduction (Warren+ 2005) 4.1 -6.1 keV 1.63-2.26 keV 0.95-1.26 keV,
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1. Tycho’s SNR - introduction Fast expansion (0.45”/yr) Slow expansion (0.15”/yr) X-ray (Suzaku 0.1-12 keV) Molecular cloud (12CO) Hot dust (AKARI 18um) Expansion velocity from VLA 1375 Hz (Reynoso+ 1997) - Observed in 1572 by Tycho Brahe - Type Ia - Distance = 1.5 ~ 3.1 kpc - Detection of IR emissioin + IRAS (Schwaltz 1995) + ISO/ISOCAM (Douvion+ 2001) - Size = 8’ (5.3pc) - Extensively studied in X-ray, Radio and Optical Tycho’s SNR
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2. AKARI infrared observations X-ray (Suzaku 0.1-12 keV) Molecular cloud (12CO) Hot dust (AKARI 18um) Expansion velocity from VLA 1375 Hz (Reynoso+ 1997) - Observed in 1572 by Tycho Brahe - Type Ia - Distance = 1.5 ~ 3.1 kpc - Detection of IR emissioin + IRAS (Schwaltz 1995) + ISO/ISOCAM (Douvion+ 2001) - Size = 8’ (5.3pc) - Extensively studied in X-ray, Radio and Optical Tycho’s SNR We investigated physical state and origin of the MIR emission using AKARI (9, 15, 18, 24, 65, 90, 140, 160um) images.
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Flux (Jy) Infrared SED of dust emission 3. Overall picture Flux (Jy) Total SED (AKARI+IRAS) is characterized by two temperatures Dust temperature ⇒ higher at outer edge (shock front) MIR map limb-brightened shell structure ⇒ Shock heated dust of IS origin Infrared SED of dust emission 15/24 m intensity ratioAKARI 9 m bandAKARI 18 m band 0.2 0.3 (100 ~ 136 K) (PAH)(Hot dust) T 1 ~ 25 K ISM T 2 ~ 95 K Shock heated dust
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⇒ 150 yr ⇔ 500 yr (Age of the SNR) (Draine & Salpeter 1979, Tielens et al. 1994) Time scale of the dust destruction by sputtering in hot plasma Time scale of PAH destruction is 1/100 ~ 1/1000 faster ⇒ < 1 yr... vanished C=0.79 (silicate), a=1nm, T=8.4x10 K 、 n H =10 cm 6 -3 Flux (Jy) Infrared SED of dust emission 15/24 m intensity ratioAKARI 9 m bandAKARI 18 m band 0.2 0.3 (100 ~ 136 K) (PAH)(Hot dust) ⇒ 150 yr ⇔ 500 yr (Age of the SNR) (Draine & Salpeter 1979, Tielens et al. 1994) Time scale of the dust destruction by sputtering in hot plasma Time scale of PAH destruction is 1/100 ~ 1/1000 faster ⇒ < 1 yr... vanished C=0.79 (silicate), a=1nm, T=8.4x10 K 、 n H =10 cm 6 -3 3. Overall picture T 1 ~ 25 K ISM T 2 ~ 95 K Shock heated dust 150 yr500 yr atom ISM dust is heated at the shock front and destructed by the sputtering in the post-shock hot-plasma ⇒ Shell structure of ~ 100 K
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Flux (Jy) Infrared SED of dust emission 15/24 m intensity ratioAKARI 9 m bandAKARI 18 m band 0.2 0.3 (100 ~ 136 K) (PAH)(Hot dust) C=0.79 (silicate), a=1nm, T=8.4x10 K 、 n H =10 cm ⇒ 150 yr ⇔ 500 yr (Age of the SNR) (Draine & Salpeter 1979, Tielens et al. 1994) Time scale of the dust destruction by sputtering in hot plasma Time scale of PAH destruction is 1/100 ~ 1/1000 shorter ⇒ < 1 yr... vanished 6 -3 3. Overall picture ISM dust is heated at the shock front and destructed by the sputtering in the post-shock hot-plasma ⇒ Shell structure of ~ 100 K We focus on the two bright spots at NE and NW boundaries. NENW
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- Large amount of cold dust at NE Spatial distribution of molecular gas, cold dust ⇒ SNR is interacting with dense medium at NE boundary ⇒ NW is relatively rich in warm dust compared with amount of molecular gas NENW Hot dust Gas (H 2 ) 2M 20M 2x10 M - 4 10 4 5 2x10 M - 4 -60 ~ -63 km/s ~ 100 K Ratio Gas/dust AKARI (cold dust) AKARI (cold dust) Flux (Jy) NENW Infrared SED of dust emission Local SED for NE region 4.1. Origin of NE and NW emission
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Ejecta origin ISM origin ⇒ The NW warm dust could have an SN ejecta origin AKARI 18μm intensity map ー Blast wave ー Conduct discontinuity (Warren+ 2008) Contact discontinuity Blast wave Cold ISM Heated ISM Ejecta from SNR Schematic view around blast wave 4.2. Origin of dust emission at NW boundary
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-Featureless continuum (No lines, dust features) -Composed of pure Fe? Image : AKARI mid-IR (15μm) Contour: Hα Spitzer / IRS 5~36μm spectrum IRS spectrum of Cas A (Rho+ 2008) 4.3. Composition of newly formed dusts
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Infrared observations of Tycho’s SNR (AKARI 9-160μm) ⇒ Physical state (temperature, heating source) and origin of hot dusts Overall picture: Dusts of an ISM origin are heated and destroyed in the hot plasma NE region: Interaction with dense ISM NW region: Hot dusts without dense ISM - small gas/hot dust mass ratio - located inside the contact discontinuity ⇒ SN ejecta origin ? First suggestion of dust formation in Type Ia SNR → impact on the transmigration of the ISM in our galaxy and early universe. Demonstrates advantage of AKARI diffuse maps combined with X-ray and 12 CO maps. 5. Summary
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II. Mapping observations of [Fe II] lines and dust emission of IC443 by IRSF & AKARI Kokusho, T., et al. in prep.
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1. Introduction □ IC443 - Type II (Troja+ 2008) - Distance: ~1.5 kpc - Size: 45 amin (20 pc) - Age: ~10 4 yr - Heavy interaction with the ISM (Saken+ 1992) - Over-ionized X-ray plasma Center-filled, rapid cooling? (Kawasaki+ 2002) - [Fe II] line emission in NE part of the remnant → J-shock (Graham+ 1987) - H 2 line emission in south part of the remnant → C-shock (Rho+ 2001) IC443 Hα image
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30’ Saken+1992 1. Introduction □ IC443 - Type II (Troja+ 2008) - Distance: ~1.5 kpc - Size: 45 amin (20 pc) - Age: ~10 4 yr - Heavy interaction with the ISM (Saken+ 1992) - Over-ionized X-ray plasma Center-filled, rapid cooling? (Kawasaki+ 2002) - [Fe II] line emission in NE part of the remnant → J-shock (Graham+ 1987) - H 2 line emission in south part of the remnant → C-shock (Rho+ 2001) IC443 IRAS 100μm image
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1. Introduction □ IC443 - Type II (Troja+ 2008) - Distance: ~1.5 kpc - Size: 45 amin (20 pc) - Age: ~10 4 yr - Heavy interaction with the ISM (Saken+ 1992) - Over-ionized X-ray plasma Center-filled, rapid cooling? (Kawasaki+ 2002) - [Fe II] line emission in NE part of the remnant → J-shock (Graham+ 1987) - H 2 line emission in south part of the remnant → C-shock (Rho+ 2001) IC443 ASCA 0.7-10 keV image 30’ Contours: softness ratio (Kawasaki+ 2002)
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1. Introduction □ IC443 - Type II (Troja+ 2008) - Distance: ~1.5 kpc - Size: 45 amin (20 pc) - Age: ~10 4 yr - Heavy interaction with the ISM (Saken+ 1992) - Over-ionized X-ray plasma Center-filled, rapid cooling? (Kawasaki+ 2002) - [Fe II] line emission in NE part of the remnant → J-shock (Graham+ 1987) - H 2 line emission in south part of the remnant → C-shock (Rho+ 2001) IC443 2MASS image Blue: J, green: H, red: Ks-band (blue; [Fe II],Pβ, red: H 2 )
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1. Introduction □ IC443 - Type II (Troja+ 2008) - Distance: ~1.5 kpc - Size: 45 amin (20 pc) - Age: ~10 4 yr - Heavy interaction with the ISM (Saken+ 1992) - Over-ionized X-ray plasma Center-filled, rapid cooling? (Kawasaki+ 2002) - [Fe II] line emission in NE part of the remnant → J-shock (Graham+ 1987) - H 2 line emission in south part of the remnant →C-shock (Rho+ 2001) IC443 2MASS image Blue: J, green: H, red: Ks-band (blue; [Fe II],Pβ, red: H 2 ) Based on observations of [Fe II] line emissions and IR dust emissions, we discuss on supply of Fe element from SNRs to the ISM.
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2. FIR images from AKARI all-sky survey 65 m 90 m 140 m160 m 90MJy/sr110MJy/sr 240MJy/sr 300MJy/sr 65 90140160 dust [CII][OI]
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2. FIR images from AKARI all-sky survey 90 m 140 m 110MJy/sr 240MJy/sr 65 90140160 dust [CII][OI] [CII] Contours: 140 m
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2. FIR images from AKARI all-sky survey 90 m 140 m 110MJy/sr 240MJy/sr 65 90140160 dust [CII][OI] [CII] Contours: 140 m AKARI 2.5 – 5 m spectra
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2. FIR images from AKARI all-sky survey 65 m 160 m 90MJy/sr 300MJy/sr 90 m 140 m 110MJy/sr 240MJy/sr 65 90140160 dust [CII][OI]
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2. FIR images from AKARI all-sky survey 65 m 160 m 90MJy/sr 300MJy/sr 90 m 140 m 110MJy/sr 240MJy/sr 65 90140160 dust [CII][OI] Broad bands tracing dust emission with small contribution of [OI] 63μm and [CII] 158μm line emissions. → Derive hot-dust mass distribution by fitting dust SEDs composed of Spitzer 24μm, AKARI 90μm, and 140μm intensities.
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3. Observations of [Fe II] lines [Fe II] 1.256μm : 4 D 7/2 → 6 D 9/2 [Fe II] 1.644μm : 4 D 7/2 → 4 F 9/2 Transitions from same level. → The intensity ratio is theoretically derived from Einstein A-coeffs. (Narayan+ 2010) → Accurate Av correction → Av-free [Fe II] intensity Narrow-band filters for [Fe II] 1.256μm & 1.644μm IRSF telescope of Nagoya Univ. (at South Africa) Nagayama+ 2008 (μm) (%) J J H H 1.256 1.644 Pβ
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3. Origin of [Fe II] emission ISM: ~98 % of Fe is depleted on dust grains [Fe II] 1.64μm / Br γ ~1 SNRs: Fast shocks (~100 km/s) ⇒ destruction of dust grains [Fe II]1.64μm / Br γ ~100 (Koo+ 2007) [Fe II] IP: 7.9 eV (< 13.6 eV) In equilibrium hot plasma (T=10 7 K), most of Fe is Fe 20+ no Fe 1+ → Tracers of fast shocks, young SNRs (Mazzotta+ 1998) atom
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3. [Fe II] distribution IRSF [Fe II] 1.256μm IRSF [Fe II] 1.644μm → Derive Fe mass distribution from Av-free [Fe II] intensities assuming LTE with T~10 4 K. (erg/s/cm 2 /sr) 2MASS J, H, Ks
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3. [Fe II] distribution [Fe II]1.644μm Contours: Hα + [NII] AKARI 18μm (hot dust) AKARI 9μm (PAH, H 2 lines) atom
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→ M dust 4. Comparison of dust mass and Fe mass □ Dust mass related to the SNR □ Fe + mass SED fitting by 2 temp. B.B. - Hot dust … shock heated - Cold dust … (foreground or background ?) Hot dust component assuming, a=0.1μm, Q abs =30cm 2 g -1 (Hildebrand 1983) (μm) M Fe = N ・ (unit mass)
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4. Discussion Fe / hot dust mass ratio 10’ - Fe / hot dust mass ratio shows excess in some regions. Solar abundance ~ 0.4 (excess amount ~10 6 M sun ) Dust mass Fe + mass AKARI IR SED IRSF [Fe II]
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4. Comparison of time scales Fe 1+ disappears at ionization equilibrium (T e =10 7 K) □ Life time of dust grains in hot plasma: □ Time scale to reach ionization equilibrium : (Darine+ 1979) In the hot plasma of T e =10 7, n e =1.7 cm -1, a dust =0.1μm (Yamaguchi+ 2009, Petre+ 1988) (yr) (Masai 1994) ⇒ ~ 1x10 5 yr ⇒ ~ 2x10 4 yr → [Fe II] line emissions attenuate faster than IR dust emission.
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4. Discussion Fe / hot dust mass ratio 10’ ⇒ Fe ejected from SNR ? - Fe / hot dust mass ratio shows excess in some regions. Solar abundance ~ 0.4 (excess amount ~10 6 M sun ) Dust mass Fe + mass AKARI IR SED IRSF [Fe II] - [Fe II] line emissions attenuate faster than IR dust emission.
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5. Summary AKARI mid-& far-infrared & IRSF near-IR observation of IC443 Northern region: [Fe II] originated by dust sputtering in J-shock Southern region: H 2 and [O I] in C-shock Accurate correction of extinction by observing two [Fe II] lines Fe + / hot dust mass ratio shows excess in some parts of IC443 → [Fe II] line emissions attenuate faster than IR dust emission → Fe of an SN ejecta origin ?
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III. Summary Interaction of SNRs with the dense ISM → IR observations Fe in ejecta of SNRs Tycho’s SNR (10 -4 M sun ) … Type Ia IC443 (10 -6 M sun ) … Type II Utilization of AKARI All-Sky diffuse maps (shock tracer, past shock tracer, as well as indicators of dust temperature, dust mass, etc.)
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