Balmer Filaments in Tycho’s Supernova Remnant: An Interplay between Cosmic-ray and Broad-neutral Precursors
Balmer Filaments in Tycho’s Supernova Remnant: An Interplay between Cosmic-ray and Broad-neutral Precursors
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DOI：
10.3847/1538-4357/aa8323
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发表时间：
2017-08
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通讯作者：
S. Knežević;R. Läsker;G. van de Ven;J. Font;J. Raymond;C. Bailer-Jones;J. Beckman;G. Morlino;P. Ghavamian;J. Hughes;K. Heng
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作者：
S. Knežević;R. Läsker;G. van de Ven;J. Font;J. Raymond;C. Bailer-Jones;J. Beckman;G. Morlino;P. Ghavamian;J. Hughes;K. Heng
我们介绍了超新星遗迹第谷（SN 1572）中巴尔末细丝的Hα光谱观测和详细建模。我们在威廉·赫歇尔望远镜上使用GHαFaS（Galaxy Hα Fabry-Pérot Spectrometer），其视场为3.′4 × 3.′4，像素尺度为0.″2，在1″视宁度下的分辨率为8.1 km s−1，持续时间为2.10 hr，产生了82个空间光谱箱，可以分辨整个SN 1572东北边缘的窄Hα线。因此，我们第一次可以减轻来自未分辨的微分运动的人为谱线展宽，并在变化的激波和周围介质条件下探测Hα发射参数。宽Hα线在392 km s−1的光谱覆盖范围内仍然无法分辨。我们采用贝叶斯推理，以获得可靠的参数置信区间，并量化的证据与多个线组件的模型。在95%的置信水平下，所有箱和模型的Hα窄线（NL）半高宽中值为W NL =（54.8 ± 1.8）km s−1，在箱之间的变化范围为[35，72] km s−1，与固有（热）20 km s−1相比明显加宽。可能的线分裂被考虑在内，在约18%的细丝中显着，并且可能是由于剩余的投影效应。我们还发现了广泛的证据，证明中间线发射是一种宽中性的前兆，其中值W IL =（180 ± 14）km s−1（95%置信度）。最后，我们给出了残骸系统速度的测量值，V LSR = − 34 km s−1，并绘制了差分视线运动图。我们的研究结果证实了第谷遗迹中激波前兆的存在和相互作用。特别是，我们表明，超热NL发射是近普遍的SN 1572，并且，在没有替代解释的情况下，碰撞SNR冲击构成了一个可行的加速源银河TeV宇宙射线质子。
We present Hα spectroscopic observations and detailed modeling of the Balmer filaments in the supernova remnant (SNR) Tycho (SN 1572). We used GHαFaS (Galaxy Hα Fabry–Pérot Spectrometer) on the William Herschel Telescope with a 3.′4 × 3.′4 field of view, 0.″2 pixel scale, and σ instr = 8.1 km s−1 resolution at 1″ seeing for ∼10 hr, resulting in 82 spatial−spectral bins that resolve the narrow Hα line in the entire SN 1572 northeastern rim. For the first time, we can therefore mitigate artificial line broadening from unresolved differential motion and probe Hα emission parameters in varying shock and ambient medium conditions. Broad Hα line remains unresolved within spectral coverage of 392 km s−1. We employed Bayesian inference to obtain reliable parameter confidence intervals and to quantify the evidence for models with multiple line components. The median Hα narrow-line (NL) FWHM of all bins and models is W NL = ( 54.8 ± 1.8 ) km s−1 at the 95% confidence level, varying within [35, 72] km s−1 between bins and clearly broadened compared to the intrinsic (thermal) ≈20 km s−1. Possible line splits are accounted for, significant in ≈ 18 % of the filament, and presumably due to remaining projection effects. We also find widespread evidence for intermediate-line emission of a broad-neutral precursor, with a median W IL = ( 180 ± 14 ) km s−1 (95% confidence). Finally, we present a measurement of the remnant’s systemic velocity, V LSR = − 34 km s−1, and map differential line-of-sight motions. Our results confirm the existence and interplay of shock precursors in Tycho’s remnant. In particular, we show that suprathermal NL emission is near-universal in SN 1572, and that, in the absence of an alternative explanation, collisionless SNR shocks constitute a viable acceleration source for Galactic TeV cosmic-ray protons.