标题： 早期伽马射线对Fermi大面积望远镜观测核心塌缩超新星2023ixf中的宇宙射线加速的限制 显示英文标题

标题： Early-time gamma-ray constraints on cosmic-ray acceleration in the core-collapse SN 2023ixf with the Fermi Large Area Telescope

摘要： 尽管数十年来超新星遗迹（SNRs）被认为是银河系中最相关的宇宙射线（CR）加速器，但超新星（CCSNe）可能在它们演化的最早阶段加速粒子，从而对银河系中的宇宙射线能量预算做出贡献。 确实有一些超新星遗迹与TeV伽马射线相关联，但在超新星膨胀早期阶段质子加速效率仍然主要未被约束。 对附近星系M101中的II型超新星2023ixf的多波段观测开启了在红超巨星（RSG）恒星前身坍缩后几天内限制宇宙射线加速的可能性。 通过这项工作，我们旨在提供一个现象学的、准模型无关的约束，在光子能量超过100 MeV时，此次事件中的宇宙射线加速效率。 我们对费米大面积望远镜（Fermi LAT）的伽马射线数据进行了最大似然分析，时间范围直至超新星爆炸后一个月。 我们搜索了其膨胀冲击波的高能辐射，并假设符合标准扩散激波加速的幂律质子分布，估计潜在的强子宇宙射线能量储备。 我们没有发现来自超新星2023ixf的显著伽马射线发射。 然而，我们的非检测提供了对Ia型超新星非常早期膨胀期间转移给强子宇宙射线群体的能量的第一个限制。 在合理假设下，我们的限制意味着最低的加速效率仅为1%，这与普通超新星中常见的10%估计值不一致。 但是，这个结果高度依赖于假定的周围介质几何结构，通过挑战球对称性，这一结果可以放松回到10%。 在确定II型超新星是否确实是早期有效的宇宙射线加速器之前，需要更复杂的、非均匀的冲击波和前身环境表征。 显示英文摘要

摘要： While SNRs have been considered the most relevant Galactic CR accelerators for decades, CCSNe could accelerate particles during the earliest stages of their evolution and hence contribute to the CR energy budget in the Galaxy. Some SNRs have indeed been associated with TeV gamma-rays, yet proton acceleration efficiency during the early stages of an SN expansion remains mostly unconstrained. The multi-wavelength observation of SN 2023ixf, a Type II SN in the nearby galaxy M101, opens the possibility to constrain CR acceleration within a few days after the collapse of the RSG stellar progenitor. With this work, we intend to provide a phenomenological, quasi-model-independent constraint on the CR acceleration efficiency during this event at photon energies above 100 MeV. We performed a maximum-likelihood analysis of gamma-ray data from the Fermi Large Area Telescope up to one month after the SN explosion. We searched for high-energy emission from its expanding shock, and estimated the underlying hadronic CR energy reservoir assuming a power-law proton distribution consistent with standard diffusive shock acceleration. We do not find significant gamma-ray emission from SN 2023ixf. Nonetheless, our non-detection provides the first limit on the energy transferred to the population of hadronic CRs during the very early expansion of a CCSN. Under reasonable assumptions, our limits would imply a maximum efficiency on the CR acceleration of as low as 1%, which is inconsistent with the common estimate of 10% in generic SNe. However, this result is highly dependent on the assumed geometry of the circumstellar medium, and could be relaxed back to 10% by challenging spherical symmetry. A more sophisticated, inhomogeneous characterisation of the shock and the progenitor's environment is required before establishing whether or not Type II SNe are indeed efficient CR accelerators at early times.