研究超新星遗迹 IC 443 和 W51 C 中已灭绝 PeVatron 活动的特征
Investigating signatures of extinct PeVatron activity in supernova remnants IC 443 and W51 C
- Sapienza Università di Roma（罗马第一大学）
- Istituto Nazionale di Fisica Nucleare, Sezione di Roma（意大利国家核物理研究所罗马分部）
- INAF Osservatorio Astrofisico di Arcetri（意大利国家天体物理研究所阿切尔塞天文台）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究通过时间依赖解析模型分析超新星遗迹 IC 443 和 W51 C 中受限与逃逸质子的强子辐射，验证其伽马射线起源，并约束粒子最大能量、磁场放大及加速效率（1-12%），发现最大能量低于 PeV 膝所需值。
AI中文摘要：
背景。超新星遗迹（SNRs）是非热粒子的更新来源，也是银河系宇宙射线（CRs）的主要贡献者。来自中年超新星遗迹（如 IC 443 和 W51 C）的近期超高能（UHE）伽马射线数据凸显了这些系统在粒子加速中的关键作用。理解超新星遗迹对 PeV 宇宙射线的贡献需要对加速粒子如何从其激波逃逸并释放到银河系内部进行详细建模。目标。我们旨在通过研究超新星遗迹中受限和逃逸质子发生强子碰撞所产生的预期次级辐射，并将这些辐射与近期超高能观测进行比较，来批判性地评估超新星遗迹作为银河系宇宙射线起源的范式。方法。通过一个描述超新星遗迹前向激波处粒子加速的时间依赖解析模型，我们研究了粒子从膨胀到均匀环境中的激波逃逸，并在超新星遗迹内部和外部扩散的过程。结果。我们的结果支持这样的解释：W51 C 和 IC 443 的伽马射线发射来自受限和逃逸质子的强子发射，从而使我们能够对这些系统中的粒子最大能量、磁场放大过程和宇宙射线加速效率得出可靠的约束。结论。我们发现，当加速粒子的谱正比于 p^-4（p^-4.3）且原位扩散系数比银河系平均值低 3-10 倍时，加速效率在 1-10%（2-12%）范围内。另一方面，粒子曾经达到的最大能量比解释仅由超新星遗迹产生的宇宙射线膝所需的 PeV 能量低几倍。
英文摘要：
Context. Supernova remnants (SNRs) are renewed sources of non-thermal particles and the main contributors of Galactic cosmic rays (CRs). Recent ultra-high energy (UHE) gamma-ray data from middle-aged SNRs, such as IC 443 and W51 C, highlight the key role of these systems for particle acceleration. Understanding SNR contribution to PeV CRs requires a detailed modelling about how accelerated particles escape their shocks and are released inside the Galaxy. Aims. We aim at critically assessing the SNR paradigm for the origin of Galactic CRs by investigating the expected secondary radiation produced by hadronic collisions of confined and escaping protons in SNRs, and compare these to recent UHE observations. Methods. Through a time-dependent analytical model describing particle acceleration at the SNR forward shock, we investigate particle escape from the shock expanding into uniform environment and diffusing inside and outside the SNR. Results. Our results support the interpretation that the gamma-ray emission from W51 C and IC 443 is due to hadronic emission from both confined and escaping protons, allowing us to derive robust constraints on the particle maximum energy, the magnetic field amplification process, and the CR acceleration efficiency in these systems. Conclusions. We find that the acceleration efficiency is in the range 1 - 10% (2 - 12%) when the spectrum of accelerated particles is proportional to p^-4 (p^-4.3) and the in-situ diffusion coefficient is suppressed by a factor of 3-10 compared to the average Galactic value. On the other hand, the particle maximum energy ever achieved falls, by a factor of a few, below the PeV energy required to explain the CR knee in the context of SNRs only.
