In this decade, GeV/TeV gamma-ray observations of several supernova remnants (SNRs) have implied that accelerated particles are escaping from their acceleration sites. However, when and how they escape from the SNR vicinities are yet to be understood. Recent studies have suggested that the particle escape might develop with thermal plasma ages of the SNRs. In this paper, we present a systematic study on time evolution of particle escape using thermal X-ray properties and gamma-ray spectra. We used 38 SNRs which associate with GeV/TeV gamma-ray emissions. We conducted spectral fittings on the gamma-ray spectra using exponential cutoff power law and broken power law models to estimate the exponential cutoff or the break energies, both of which are indicators of particle escape. The plots of the gamma-ray cutoff/break energies over the plasma ages show similar tendencies to those predicted by simple theories of the particle escape under conditions in which a shock is interacting with thin interstellar medium or clouds. The particle escape timescale is estimated as $\sim$100 kyr from decreasing trends of the total energy of the confined protons with the plasma age. The large dispersions of the cutoff/break energies of the data may suggest an intrinsic variety of particle escape environments. This might be the cause of the complicated Galactic cosmic-ray spectral shape measured on Earth.

中文翻译：

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超新星遗迹高能粒子逃逸时间尺度的热X射线特性研究

在这十年中，对几个超新星遗迹 (SNR) 的 GeV/TeV 伽马射线观测表明，加速粒子正在逃离它们的加速位置。然而，它们何时以及如何逃离 SNR 附近尚待了解。最近的研究表明，粒子逃逸可能随着 SNR 的热等离子体年龄而发展。在本文中，我们使用热 X 射线特性和伽马射线光谱对粒子逃逸的时间演化进行了系统研究。我们使用了 38 个与 GeV/TeV 伽马射线发射相关的 SNR。我们使用指数截止幂律和破碎幂律模型对伽马射线光谱进行光谱拟合，以估计指数截止或断裂能，这两者都是粒子逃逸的指标。等离子年龄的伽马射线截止/断裂能图显示出与在冲击与薄的星际介质或云相互作用的条件下粒子逃逸的简单理论预测的趋势相似。根据受限质子总能量随等离子体年龄的下降趋势，粒子逃逸时间尺度估计为 $\sim$100 kyr。数据的截止/断裂能的大分散可能表明粒子逃逸环境的内在多样性。这可能是在地球上测量到的复杂的银河宇宙射线光谱形状的原因。根据受限质子总能量随等离子体年龄的下降趋势，粒子逃逸时间尺度估计为 $\sim$100 kyr。数据的截止/断裂能的大分散可能表明粒子逃逸环境的内在多样性。这可能是在地球上测量到的复杂的银河宇宙射线光谱形状的原因。根据受限质子总能量随等离子体年龄的下降趋势，粒子逃逸时间尺度估计为 $\sim$100 kyr。数据的截止/断裂能的大分散可能表明粒子逃逸环境的内在多样性。这可能是在地球上测量到的复杂的银河宇宙射线光谱形状的原因。