Modeling Hadronic Gamma-Ray Emissions from Solar Flares and Prospects for Detecting Nonthermal Signatures from Protostars
Modeling Hadronic Gamma-Ray Emissions from Solar Flares and Prospects for Detecting Nonthermal Signatures from Protostars
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DOI：
10.3847/1538-4357/acb649
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发表时间：
2022-11
期刊：
影响因子：
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通讯作者：
S. Kimura;S. Takasao;K. Tomida
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文献类型：
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作者：
S. Kimura;S. Takasao;K. Tomida
我们研究了太阳耀斑脉冲阶段的伽马射线发射和原恒星耀斑非热信号的可探测性。高能太阳耀斑发出GeV能量的高能伽马射线，但其产生机制和发射地点尚不清楚。年轻的恒星物体，包括原恒星，也表现出发光的X射线耀斑，但由于强烈的遮挡，耀斑活动的触发机制尚不清楚。毫米/亚毫米和伽马射线波段的非热信号对于探测原恒星耀斑是有用的，因为它们具有很强的穿透能力。我们建立了一个太阳耀斑脉冲阶段的非热发射模型，其中在终止激波时加速的宇宙射线质子通过与蒸发等离子体的强核相互作用产生高能伽马射线。该模型可以再现太阳耀斑脉冲相的伽马射线数据。我们将我们的模型应用于原恒星耀斑，并表明如果原恒星耀斑中的粒子加速是有效的，切伦科夫望远镜阵列将能够探测到TeV能量的伽马射线。与质子一起加速的非热电子可以通过同步辐射发出强烈的毫米和亚毫米信号，其功率与从年轻恒星观察到的高能毫米/亚毫米瞬变一致。未来来自原恒星的伽马射线和毫米/亚毫米观测，与硬X射线观测相协调，将揭开原恒星耀斑的非热粒子产生和触发机制。
We investigate gamma-ray emission in the impulsive phase of solar flares and the detectability of nonthermal signatures from protostellar flares. Energetic solar flares emit high-energy gamma rays of GeV energies, but their production mechanism and emission site are still unknown. Young stellar objects, including protostars, also exhibit luminous X-ray flares, but the triggering mechanism of the flaring activity is still unclear owing to the strong obscuration. Nonthermal signatures in millimeter/submillimeter and gamma-ray bands are useful to probe protostellar flares owing to their strong penetration power. We develop a nonthermal emission model of the impulsive phase of solar flares, where cosmic-ray protons accelerated at the termination shock produce high-energy gamma rays via hadronuclear interaction with the evaporation plasma. This model can reproduce gamma-ray data in the impulsive phase of a solar flare. We apply our model to protostellar flares and show that the Cherenkov Telescope Array will be able to detect gamma rays of TeV energies if particle acceleration in protostellar flares is efficient. Nonthermal electrons accelerated together with protons can emit strong millimeter and submillimeter signals via synchrotron radiation, whose power is consistent with the energetic millimeter/submillimeter transients observed from young stars. Future gamma-ray and millimeter/submillimeter observations from protostars, coordinated with a hard X-ray observation, will unravel the nonthermal particle production and triggering mechanism of protostellar flares.