I. Origin of the dust emission from Tycho’s SNR

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 SNRsIshihara Daisuke (Nagoya Univ.)

I. Origin of the dust emission from Tycho’s SNR

Ishihara, D., et al. 2010

- 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


- Type Ia




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,

1. Tycho’s SNR - introduction

Fastexpansion(0.45”/yr)

Slowexpansion(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)


- Type Ia




Radio and Optical

Tycho’s SNR

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)


- Type Ia




Radio and Optical

Tycho’s SNR

We investigated physical state and origin of the MIR emissionusing AKARI (9, 15, 18, 24, 65, 90, 140, 160um) images.

Flux

(Jy)

Infrared SED of dust emission

3. Overall pictureFl

ux (J

y)

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


15/24mm intensity ratioAKARI 9mm band AKARI 18mm band

0.2 0.3

(100 ～ 136 K)(PAH) (Hot dust)

T1 ～ 25 K

ISMT2 ～ 95 K

Shock heated

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 is1/100 ～ 1/1000 faster

⇒ < 1 yr . . . vanished

C=0.79 (silicate), a=1nm, T=8.4x10 K 、 nH=10 cm

6 -3Flux

(Jy)



0.2 0.3

(100 ～ 136 K)(PAH) (Hot dust)

⇒150 yr⇔ 500 yr (Age of the SNR)



Time scale of PAH destruction is1/100 ～ 1/1000 faster


C=0.79 (silicate), a=1nm, T=8.4x10 K 、 nH=10 cm

6 -3

3. Overall picture

T1 ～ 25 K

ISMT2 ～ 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

Flux

(Jy)



0.2 0.3

(100 ～ 136 K)(PAH) (Hot dust)

C=0.79 (silicate), a=1nm, T=8.4x10 K 、 nH=10 cm ⇒150 yr⇔ 500 yr (Age of the SNR)



Time scale of PAH destruction is1/100 ～ 1/1000 shorter


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.

NE NW

- 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

NE NW

Hot dustGas (H2) 2M20M

2x10 M- 4

10 4 10 5

2x10 M- 4

-60 ～ -63 km/s

～ 100 KRatio

Gas/dust

AKARI(cold dust)

AKARI(cold dust)

Flux

(Jy)

NE NW


Local SED for NE region

4.1. Origin of NE and NW emission

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)

ContactdiscontinuityBlast wave

ColdISM

HeatedISMEjecta

from SNR

Schematic view around blast wave

4.2. Origin of dust emission at NW boundary

- 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

• 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 12CO maps.

5. Summary

II. Mapping observations of [Fe II] lines and dust emission of IC443 by IRSF & AKARI

Kokusho, T., et al. in prep.

1. Introduction□ IC443- Type II (Troja+ 2008)- Distance: ~1.5 kpc- Size: 45 amin (20 pc)- Age: ~104 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)- H2 line emission in south part of the remnant → C-shock (Rho+ 2001)

IC443 Hα image

30’

Saken+1992


IC443 IRAS 100μm image


IC443 ASCA 0.7-10 keV image

30’

Contours: softness ratio(Kawasaki+ 2002)


IC443 2MASS imageBlue: J, green: H, red: Ks-band(blue; [Fe II],Pβ, red: H2)

1. Introduction□ IC443- Type II (Troja+ 2008)- Distance: ~1.5 kpc- Size: 45 amin (20 pc)- Age: ~104 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)- H2 line emission in south part of the remnant →C-shock (Rho+ 2001)

IC443 2MASS imageBlue: J, green: H, red: Ks-band(blue; [Fe II],Pβ, red: H2)

Based on observations of [Fe II] line emissions and IR dust emissions,we discuss on supply of Fe element from SNRs to the ISM.

2. FIR images from AKARI all-sky survey65mm 90mm

140mm 160mm

90MJy/sr 110MJy/sr

240MJy/sr 300MJy/srl

65 90 140160

dust[CII][OI]

2. FIR images from AKARI all-sky survey90mm

140mm

110MJy/sr

240MJy/srl

65 90 140160

dust[CII][OI]

[OI]

[CII]

Contours: 140mm


140mm

110MJy/sr

240MJy/srl

65 90 140160

dust[CII][OI]

[OI]

[CII]

Contours: 140mm

AKARI 2.5 – 5 mm spectra


160mm

90MJy/sr

300MJy/sr

90mm

140mm

110MJy/sr

240MJy/srl

65 90 140160

dust[CII][OI]


160mm

90MJy/sr

300MJy/sr

90mm

140mm

110MJy/sr

240MJy/srl

65 90 140160

dust[CII][OI]

Broad bands tracing dust emissionwith 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.

3. Observations of [Fe II] lines[Fe II] 1.256μm : 4D7/2 → 6D9/2[Fe II] 1.644μm : 4D7/2 → 4F9/2

Transitions from same level.→ The intensity ratio is theoretically derived from Einstein A-coeffs. (Narayan+ 2010)

→ Accurate Av correction

→ Av-free [Fe II] intensityNarrow-band filters for[Fe II] 1.256μm & 1.644μm

IRSF telescope of Nagoya Univ.(at South Africa)Nagayama+ 2008

(μm)

(%)

J H

1.256 1.644

Pβ

3. Origin of [Fe II] emission• ISM: ~98 % of Fe is depleted on dust grains

[Fe II] 1.64μm / Brγ ~1

• SNRs: Fast shocks (~100 km/s) ⇒ destruction of dust grains

[Fe II]1.64μm / Brγ~100 (Koo+ 2007)

• [Fe II] IP: 7.9 eV (< 13.6 eV)

• In equilibrium hot plasma (T=107K),most of Fe is Fe20+

no Fe1+

→ Tracers of fast shocks, young SNRs

(Mazzotta+ 1998)

atom

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~104 K.

(erg/s/cm2/sr)

2MASS J, H, Ks

3. [Fe II] distribution

[Fe II]1.644μmContours: Hα + [NII] AKARI 18μm

(hot dust)

AKARI 9μm(PAH, H2 lines)

atom

→ Mdust

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 dustcomponent

assuming, a=0.1μm, Qabs=30cm2g-

1(Hildebrand 1983)

(μm)

MFe = N ・ (unit mass)

4. Discussion

Fe / hot dust mass ratio

10’

- Fe / hot dust mass ratio shows excess in some regions.

Solar abundance ~ 0.4

(excess amount ~106 Msun)

Dust mass Fe+ mass

AKARI IR SED IRSF [Fe II]

4. Comparison of time scales

Fe1+ disappears at ionization equilibrium (Te=107K)

□ Life time of dust grains in hot plasma:

□ Time scale to reach ionization equilibrium :

(Darine+ 1979)

In the hot plasma of Te=107, ne=1.7 cm-1, adust=0.1μm (Yamaguchi+ 2009, Petre+ 1988)

(yr) (Masai 1994)

⇒ ~ 1x105 yr

⇒ ~ 2x104 yr

→ [Fe II] line emissions attenuate faster than IR dust emission.

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 ~106 Msun)

Dust mass Fe+ mass

AKARI IR SED IRSF [Fe II]

- [Fe II] line emissions attenuate faster than IR dust emission.

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:

H2 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 ?

III. Summary • Interaction of SNRs with the dense ISM

→ IR observations

• Fe in ejecta of SNRsTycho’s SNR (10-4 Msun) … Type IaIC443 (10-6 Msun) … Type II

• Utilization of AKARI All-Sky diffuse maps(shock tracer, past shock tracer, as well as indicators of dust temperature, dust mass, etc.)

I. Origin of the dust emission from Tycho’s SNR

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