AI 中文总结
该研究通过SOFIA望远镜观测γ射线明亮超新星遗迹RX J1713.7-3946的电离碳，结合多波段数据分析，发现电离碳可作为宇宙射线电离示踪物，低能宇宙射线与紫外光子均可产生其发射，凸显多波段观测的重要性。
AI 中文摘要
银河系宇宙射线（CR）的起源，尤其是亚GeV能量段的宇宙射线，因难以追踪而仍不确定。低能宇宙射线的一种可能示踪物是电离碳（[C II]），在受宇宙射线诱导电离影响的区域其强度可能增强。我们利用SOFIA望远镜获得了γ射线明亮超新星遗迹（SNR）RX J1713.7-3946的[C II] 158 μm谱线发射观测数据，将这些数据与来自Mopra望远镜（¹²CO）、Nanten望远镜（¹²CO）和SGPS巡天（HI）的分子与原子气体数据，以及TeV γ射线H.E.S.S.和X射线XMM-Newton的高能发射数据进行对比。我们发现[C II]发射与原子气体的相关性比分子气体更紧密，尤其在超新星遗迹激波前沿附近区域。[C II]强度与气体柱密度的比值在整个遗迹中存在变化，峰值与TeV γ射线发射增强的区域重合。为将[C II]置于更广泛的背景中，我们研究了Herschel GOT C+巡天的指向数据，对GOT C+数据的分析显示，在恒星形成区、H II区和超新星遗迹的观测中，I[C II]/I[¹²CO]比值无显著差异。为评估碳电离的起源，我们利用光电离程序CLOUDY对[C II]发射率进行建模，假设低能宇宙射线（< 1 GeV）在超新星遗迹激波中被加速并捕获，我们发现紫外光子和宇宙射线可产生相当水平的[C II]发射。这些结果凸显了[C II]作为宇宙射线电离示踪物的潜力，以及多波段观测结合以探测超新星遗迹中宇宙射线相互作用的重要性。
英文摘要
The origin of Galactic Cosmic Rays (CRs), particularly at sub-GeV energies, remains uncertain due to their difficulty in being traced. One possible tracer of low-energy CRs is ionised carbon ([C II]), which may be enhanced in regions affected by CR-induced ionisation. We present observations of [C II] 158 $μ$m line emission across the $γ$-ray-bright supernova remnant (SNR) RX J1713.7-3946 obtained with SOFIA. These data are compared with molecular and atomic gas from Mopra ($^{12}$CO), Nanten ($^{12}$CO) and SGPS (HI), and high-energy emission from TeV $γ$-ray H.E.S.S. and X-ray XMM-Newton. We find [C II] emission follows the atomic gas more closely than molecular gas, particularly in regions near the SNR shock front. Ratios of [C II] intensity to gas column density vary across the remnant, with peak values coinciding with regions of enhanced TeV $γ$-ray emission. To put the [C II] in a wider context, we examined pointings from the Herschel GOT C+ survey. Our analysis of the GOT C+ data shows no significant difference in the I[C II]/I[$^{12}$CO] ratio for observations towards star formation regions, HII regions and SNRs. To assess the origin of carbon ionisation, we model [C II] emissivity using the photoionisation code CLOUDY. We find UV photons and CRs can produce comparable levels of [C II] emission, assuming low-energy CRs (< 1 GeV) are accelerated and trapped within the SNR shock. These results highlight the potential of [C II] as a tracer of CR ionisation and the importance of combining multi-wavelength observations to probe CR interactions in SNRs.
Comments22 pages, 29 figures
