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arXiv 1503.04170astro-ph.HE
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超新星激波爆发前光学厚风中的无碰撞激波和TeV中微子

Collisionless Shocks and TeV Neutrinos before Supernova Shock Breakout from an Optically Thick Wind

G. Giacinti, A. R. Bell

摘要:

在超新星爆炸期间,辐射主导激波(RDS)穿过其前身。在冲击波爆发(SB)过程中,通常假设一个无碰撞冲击波(CS)代替它。我们在这里证明,对于一些实际的祖先笼罩在光学厚风,如可能SN 2008D,CS形成风深处,不久后,RDS离开核心,当靠近核心的风的密度不足以补偿由于激波引起的光子的$r^{-2}$稀释时,曲率这通常发生在激波速度为$\lesssim 0.1 {\rm c} \, (\frac{u_{\rm w}}{10\,{\rm km/s}}) (\frac{\dot{M}}{5 \cdot 10^{-4} \, {\rm M}_\odot {\rm /yr}})^{-1} (\frac{r_\ast}{10^{13}\,{\rm cm}})$时,其中$u_{\rm w}$、$\dot{M}$和$r_\ast$分别是风速、质量损失率和祖星半径。辐射CS导致爆发时光子闪光的硬光谱,这将产生X射线闪光。对于这样的祖先,宇宙射线加速将在SB之前开始。一小部分次级TeV中微子可以在第一个光子爆发之前10个多小时到达观察者,提供关于祖先不可见层的信息。

英文摘要:

During a supernova explosion, a radiation-dominated shock (RDS) travels through its progenitor. A collisionless shock (CS) is usually assumed to replace it during shock breakout (SB). We demonstrate here that for some realistic progenitors enshrouded in optically thick winds, such as possibly SN 2008D, a CS forms deep inside the wind, soon after the RDS leaves the core, and therefore significantly before SB. The RDS does not survive the transition from the core to the thick wind when the wind close to the core is not sufficiently dense to compensate for the $r^{-2}$ dilution of photons due to shock curvature. This typically happens when the shock velocity is $\lesssim 0.1 {\rm c} \, (\frac{u_{\rm w}}{10\,{\rm km/s}}) (\frac{\dot{M}}{5 \cdot 10^{-4} \, {\rm M}_\odot {\rm /yr}})^{-1} (\frac{r_\ast}{10^{13}\,{\rm cm}})$, where $u_{\rm w}$, $\dot{M}$ and $r_\ast$ are respectively the wind velocity, mass-loss rate and radius of the progenitor star. The radiative CS results in a hard spectrum of the photon flash at breakout, which would produce an X-ray flash. Cosmic ray acceleration would start before SB, for such progenitors. A fraction of secondary TeV neutrinos can reach the observer up to more than ten hours before the first photons from breakout, providing information on the invisible layers of the progenitor.

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