High-Velocity Features: A Ubiquitous Property of Type Ia Supernovae
High-Velocity Features: A Ubiquitous Property of Type Ia Supernovae
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DOI：
10.1086/429874
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发表时间：
2005-02
期刊：
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通讯作者：
P. Mazzali;S. Benetti;G. Altavilla;G. Blanc;E. Cappellaro;N. Elias-Rosa;G. Garavini;G. Garavini;A. Goobar;A. Harutyunyan;R. Kotak;B. Leibundgut;P. Lundqvist;S. Mattila;J. Méndez;S. Nobili;S. Nobili;R. Pain;A. Pastorello;F. Patat;G. Pignata;P. Podsiadlowski;P. Ruiz-Lapuente;M. Salvo;B. Schmidt;J. Sollerman;V. Stanishev;M. Stehle;C. Tout;M. Turatto;W. Hillebrandt
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文献类型：
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作者：
P. Mazzali;S. Benetti;G. Altavilla;G. Blanc;E. Cappellaro;N. Elias-Rosa;G. Garavini;G. Garavini;A. Goobar;A. Harutyunyan;R. Kotak;B. Leibundgut;P. Lundqvist;S. Mattila;J. Méndez;S. Nobili;S. Nobili;R. Pain;A. Pastorello;F. Patat;G. Pignata;P. Podsiadlowski;P. Ruiz-Lapuente;M. Salvo;B. Schmidt;J. Sollerman;V. Stanishev;M. Stehle;C. Tout;M. Turatto;W. Hillebrandt
在一些Ia型超新星(SNE Ia；例如SN2000cx)的近最大光谱中，在早于B最大值前一周观测到的可用的SN Ia光谱中，已经寻找到了高速特征(HVF)的证据。最近的观测工作已经使具有非常早期光谱的SNE Ia的数量翻了一番。值得注意的是，所有具有早期数据的SNE Ia(我们的研究培训网络样本中有7个，其他项目中的10个)在Ca II IR和Si IIλ6355系列中都或多或少地显示出这种特征的迹象。高频辐射可被解释为丰度或密度的增强。丰度的增加意味着一个以硅和钙为主的外部区域。密度增强可能是由于最高速度的SN喷出物对星周物质(CSM)的扫掠所致。在这种情况下，高密度超高频辐射表明，一个厚厚的圆盘和/或高密度的伴风环绕着爆炸中的白矮星，就像在单个简并系统中的情况一样。径向密度和丰度分布的大范围角波动也可能是原因：这可能是爆炸的根源，并表明爆燃是更有可能的爆炸机制。CSM相互作用和表面起伏可能共存，可能在光谱上留下不同的特征。在一些SNE中，HVF的速度被限制得很窄，这表明燃烧的物质被喷出。
Evidence of high-velocity features (HVFs) such as those seen in the near-maximum spectra of some Type Ia supernovae (SNe Ia; e.g., SN 2000cx) has been searched for in the available SN Ia spectra observed earlier than 1 week before B maximum. Recent observational efforts have doubled the number of SNe Ia with very early spectra. Remarkably, all SNe Ia with early data (seven in our Research Training Network sample and 10 from other programs) show signs of such features, to a greater or lesser degree, in Ca II IR and some also in the Si II λ6355 line. HVFs may be interpreted as abundance or density enhancements. Abundance enhancements would imply an outer region dominated by Si and Ca. Density enhancements may result from the sweeping up of circumstellar material (CSM) by the highest velocity SN ejecta. In this scenario, the high incidence of HVFs suggests that a thick disk and/or a high-density companion wind surrounds the exploding white dwarf, as may be the case in single degenerate systems. Large-scale angular fluctuations in the radial density and abundance distribution may also be responsible: this could originate in the explosion and would suggest a deflagration as the more likely explosion mechanism. CSM interaction and surface fluctuations may coexist, possibly leaving different signatures on the spectrum. In some SNe, the HVFs are narrowly confined in velocity, suggesting the ejection of blobs of burned material.