TIDAL TAIL EJECTION AS A SIGNATURE OF TYPE Ia SUPERNOVAE FROM WHITE DWARF MERGERS
TIDAL TAIL EJECTION AS A SIGNATURE OF TYPE Ia SUPERNOVAE FROM WHITE DWARF MERGERS
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DOI：
10.1088/0004-637x/772/1/1
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发表时间：
2013-04
期刊：
影响因子：
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通讯作者：
C. Raskin;D. Kasen
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文献类型：
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作者：
C. Raskin;D. Kasen
在两颗白色矮星合并之前，可能会有一些物质以“潮汐尾”的形式喷射出来，从而在系统周围形成一种星周介质。我们认为，从这种材料，这取决于合并的开始和最终的爆炸（假设发生一个）的Ia型超新星（SN Ia）的系统之间的滞后时间的各种观测签名。如果时间延迟相当短，那么超新星喷出物与尾部的相互作用可能会导致在无线电，光学和/或X射线波长上可检测到的冲击波发射。在稍后的时间，尾巴产生相对较宽的NaID吸收线，其速度宽度与白色矮星逃逸速度（每秒1000公里）相当。在正常的Ia超新星中没有检测到这些特征，这就限制了滞后时间要么很短（100秒），要么相当长（100年）。如果尾巴在104年的时间尺度上膨胀和冷却，那么它们可以通过光谱中狭窄的NaID和Ca ii H&K吸收线观察到，这在Ia超新星的某些部分中可以看到。使用三维和一维流体动力学代码的组合，我们模拟的质量损失从潮汐相互作用在二进制系统，以及随后的相互作用与星际介质，产生一个缓慢移动的，致密的气体壳。我们合成的NaID线轮廓通过这个壳的射线投射，并表明，在某些情况下，潮汐尾可能是负责窄的反射类似于观察到的。
The merger of two white dwarfs may be preceded by the ejection of some mass in “tidal tails,” creating a circumstellar medium around the system. We consider the variety of observational signatures from this material, which depend on the lag time between the start of the merger and the ultimate explosion (assuming one occurs) of the system in a Type Ia supernova (SN Ia). If the time lag is fairly short, then the interaction of the supernova ejecta with the tails could lead to detectable shock emission at radio, optical, and/or X-ray wavelengths. At somewhat later times, the tails produce relatively broad NaID absorption lines with velocity widths of the order of the white dwarf escape speed (∼1000 km s−1). That none of these signatures have been detected in normal SNe Ia constrains the lag time to be either very short (≲ 100 s) or fairly long (≳ 100 yr). If the tails have expanded and cooled over timescales ∼104 yr, then they could be observable through narrow NaID and Ca ii H&K absorption lines in the spectra, which are seen in some fraction of SNe Ia. Using a combination of three-dimensional and one-dimensional hydrodynamical codes, we model the mass loss from tidal interactions in binary systems, and the subsequent interactions with the interstellar medium, which produce a slow-moving, dense shell of gas. We synthesize NaID line profiles by ray casting through this shell, and show that in some circumstances tidal tails could be responsible for narrow absorptions similar to those observed.