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arXiv 1609.09093astro-ph.HE
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I型In超新星的两个不同吸收X射线分量:星周介质非球面性的证据

Two Distinct-Absorption X-Ray Components from Type IIn Supernovae: Evidence for Asphericity in the Circumstellar Medium

Satoru Katsuda, Keiichi Maeda, Aya Bamba, Yukikatsu Terada, Yasushi Fukazawa, Koji Kawabata, Masanori Ohno, Yasuharu Sugawara, Yohko Tsuboi, Stefan Immler

摘要:

我们提出了多历元X射线光谱观测的三个类型IIn超新星(SNe)2005 kd,2006 jd和2010 jl,获得钱德拉,XMM-牛顿,朱雀,和斯威夫特。先前对SN 2010 jl的广泛X射线研究表明,X射线光谱主要是热辐射,这可能是由传播到大质量拱星介质(CSM)的前向激波加热的热等离子体引起的。有趣的是,需要一个额外的软X射线组件,以重现光谱在一个周期的SN爆炸后1-2年。虽然这一成分可能与SN有关,但其来源仍然是一个悬而未决的问题。我们发现一个类似的,额外的软X射线组件从其他两个SNe IIn以及。鉴于这一发现,我们提出了一个新的解释,这个组件的起源,它是从一个向前冲击的热辐射基本上相同的硬X射线组件,但直接到达我们从一个空洞的密集CSM。也就是说,硬组分和软组分分别负责重度吸收组分和中度吸收组分。这两种组分的共存以及中等吸收的X射线组分的延迟出现是CSM非球面性的证据。我们表明,X射线光谱的演变可以定性地解释考虑一个环面状的几何致密CSM。根据我们的X射线光谱分析,我们估计环形CSM的半径约为5 × 10^{16} cm。

英文摘要:

We present multi-epoch X-ray spectral observations of three Type IIn supernovae (SNe) 2005kd, 2006jd, and 2010jl, acquired with Chandra, XMM-Newton, Suzaku, and Swift. Previous extensive X-ray studies of SN 2010jl have revealed that X-ray spectra are dominated by thermal emission, which likely arises from a hot plasma heated by a forward shock propagating into a massive circumstellar medium (CSM). Interestingly, an additional soft X-ray component was required to reproduce the spectra at a period of ~1-2 yr after the SN explosion. Although this component is likely associated with the SN, its origin remained an open question. We find a similar, additional soft X-ray component from the other two SNe IIn as well. Given this finding, we present a new interpretation for the origin of this component; it is thermal emission from a forward shock essentially identical to the hard X-ray component, but directly reaches us from a void of the dense CSM. Namely, the hard and soft components are responsible for the heavily- and moderately-absorbed components, respectively. The co-existence of the two components with distinct absorptions as well as the delayed emergence of the moderately-absorbed X-ray component would be evidence for asphericity of the CSM. We show that the X-ray spectral evolution can be qualitatively explained by considering a torus-like geometry for the dense CSM. Based on our X-ray spectral analyses, we estimate the radius of the torus-like CSM to be on the order of ~5 times 10^{16} cm.

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