小组讨论会发言小组讨论会发言

超新星遗迹中的分子壳层

2008 － 11 － 13

陈阳 on behalves of 苏扬、周鑫、杨戟、具本哲

为什么要研究为什么要研究 SNRs SNRs MCs MCs Molecular gas takes up 1/2 mass of ISM Most core-collapse SNe are located close to GMCs --- their birth places (e.g. Huang & Thaddeus 1986) 2/3 among 270 Galactic SNRs estimated to have been interacted with MCs; only 20 are confirmed (Reynoso & Mangum 2000)

Observations of MCs Observations of MCs SNRs : CO, OH, HCO+ SNRs : CO, OH, HCO+ … … 开发德令哈 ！开发 K(C)OSMA !

压缩、加热、驱动气体 激发、电离乃至离解分子 往往在小比例电离分子云内以连续型（ C 型）激波推进，伴随着双极扩散等重要物理 过程 高温、高密环境还影响气体的化学演化，伴随着本不可能的分子谱线的发射（如 OH 脉泽） 可能引发湍动和恒星形成 (e.g., Woodward 1976) 特别重要：激波与云 p-p 碰撞 0 2 ， TeV 射线源，目前热点问题之一

对分子云的物理作用：对分子云的物理作用：SN2006gy in NGC1260

CO towards SNRsCO towards SNRs

C: no CO

A survey of 26 Galactic SNRs, ~half are detected in CO line (Huang & Thaddeus 1986).Pioneer works:

W44 (Wootten 1977)

CO,13CO (J=1-0) broadening,intensified

IC443 (DeNoyer 1979)

W28 (Wootten 1981)

OH (1720MHz) towards SNRsOH (1720MHz) towards SNRsSurvey: Among 260 Galactic SNRs, 33 SNRs are detected in OH 1720MHz line (Green et al. 1997)

IC443 (DeNoyer 1979)

Pioneer

OH (1720MHz) Masers & SNRsOH (1720MHz) Masers & SNRs

Suggested mechanisms:

1. e’s (produced by X-ray & CR) excite Lyman & Werner bands of H2 FUV

2. SNR X-ray ionization ( 1015 s1) enhances OH production (H2O + FUV OH +H, Wardle 1999; Yusef-Zadeh et al.2003),

3. SN C-type shocks in MCs (50-125K, 105cm3) produce OH masers (column 1016cm2) (Lockett et al. 1999)

marking interaction between SNRs & MCs

Especially, 19 Galactic SNRs are accompanied by OH 1720 MHz masers (Green et al. 1997)!

First detection (Goss & Robinson 1968)

Theory (Green,A.J. 2002; Wardle & Yusef-Zadeh 2002))

德令哈 德令哈 COCO 、、 HCOHCO++ 、、 HCNHCN 巡测、单测计巡测、单测计划划

1. 与 SNR 位置、形态相关性，特别关注空腔（ cavity ）、壳层（ shell ）结构；

2. 相互作用的证据：激波作用区域分子气体的谱线轮廓、速度场结构、气体密度和激发温度的分布；

3. 超新星遗迹成协分子云内恒星形成的影响。

Molecular shells in SNRs?Molecular shells in SNRs?W49B: C-type shock? 3C397: 13CO shell?

Both suggested to be in wind-blown bubbles.

Wind-bubble scenarioWind-bubble scenarioOther examples suggested in wind bubbles

Kes27: shock reflection (Chen et al. 08)

N132D: hitting cavity wall (Chen et al. 03)

HI walls, all not yet confirmed to be with MCs !

DA530 (Landecker et al. 98)

Kes 69Kes 69特征：

1. 东南残段壳层 : 射电， 4.5 & 5.8 m (Spitzer)

2. 西北致密 OH 1720 MHz 脉泽， VLSR=69 km/s

3. 南缘延展 OH 1720 MHz 脉泽， VLSR=85 km/s

Kes 69: CO shellKes 69: CO shell80-81 km/s

79-82 km/s

12CO

13CO

HCO+

12CO

13CO

C18O

Blue-shifted broadening Association d = 5.2 kpc (other than 11.2 kpc)

Kes 75Kes 75特征：

1. 中间 PWN

2. 南面半个壳层 （ radio ， IR ）

3. 南面两个 X 射线亮块49-58 km/s 78-101 km/s

Kes 75: 54km/s componentKes 75: 54km/s component

N(H2) 1 cm2

Morphological correspondenceMorphological correspondence

Association d = 10.6 kpc (other than 19 or 6 kpc)

Kes 75: Chandra X-ray spectraKes 75: Chandra X-ray spectra

NH cm2

MC-shock interactionMC-shock interaction radio continuum: blast wave in ICM /slowed by clouds X-ray: hot gas (blast-heated, evaporated), ejecta NIR: 4.5 m – shocked gas (neutrals & mol.s, not PAH) 5.8 m – shocked mol. gas (H2) / ionized (FeII) 24 m – heated dust grains / shocked H2, OH

shocked molecules consistent with OH masers, HCO+ consistent with C-type shockes

Kes 69 Kes 75 Pressure balance:

>> average cloud n(H2)~60-100 cm3

Why?

Difficulties with swept-up Difficulties with swept-up scenarioscenario

Kes 69 Kes 75Age: Energy:

X-rays: vs ~ 10 km/s too small if only n0 ~ 0.1 cm3 !

Radio emission: H2 formation timescale: (1) CR acceleration needs

there would have been no molecules!

no new CRs

(2) ambipolar diffusion timescale

ta-d

B field separated, old e escaped

Molecular shells of wind-Molecular shells of wind-bubblebubble

Ring Nebula: G79.29+0.46

Imprints of massive star evolution

Natural explanation of why the shells pre-exist & what the shells are (e.g. high n_H2)

Avoid the dynamical difficulties (e.g. high E)

Kes 69 Kes 75Bubble expansion velocity:

similar to the velocity shift

Rizzo et al. (08)

A schetch for Kes 75A schetch for Kes 75N(H2) 1 cm2 N(H2) 51 cm2

NH cm2

Kes75: Kes75: -ray excess-ray excess

LX/L 10, 1/3 G21.50.9, 1/12 Crab

Partial -ray contribution from pp 0 decay ?