MAGIC observations provide compelling evidence of hadronic multi-TeV emission from the putative PeVatron SNR G106.3+2.7
MAGIC observations provide compelling evidence of hadronic multi-TeV emission from the putative PeVatron SNR G106.3+2.7
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MAGIC 观测提供了来自假定的 PeVatron SNR G106.3 2.7 强子多 TeV 发射的令人信服的证据
DOI：
10.1051/0004-6361/202244931
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发表时间：
2023
影响因子：
6.5
通讯作者：
et al.
中科院分区：
文献类型：
--
作者：
MAGIC Collaboration;Abe H.;Abe S.;Acciari V. A.;Agudo I.;Aniello T.;Ansoldi S.;Antonelli L. A.;Arbet Engels A.;Arcaro C.;Artero M.;Asano K.;et al.
背景我们银河系中某些类型的超新星遗迹 (SNR) 被认为是 PeVatron，能够将宇宙射线 (CR) 加速到 ~ PeV 能量。然而，尚未找到确凿的观察证据。 SNR G106.3+2.7 由不同的 γ 射线设备在 1–100 TeV 能量下检测到，是最有前途的 PeVatron 候选者之一。该SNR具有彗星形状，可分为具有不同物理条件的头部和尾部区域。然而，由于现有观测数据的位置精度和/或角分辨率有限，尚未确定 100 TeV 发射是在哪个区域产生的。此外，目前还不清楚γ射线发射的起源是轻子还是强子。目的与早期γ射线数据集相比，新的MAGIC数据提供了更好的角分辨率，我们的目标是通过在TeV能量下以0.1°分辨率解析SNR G106.3+2.7来揭示PeV粒子的加速位置和发射机制。方法我们使用2017 年 5 月至 2019 年 8 月期间，MAGIC 望远镜在质量削减后总共运行了 121.7 小时。分析能量阈值约为 0.2 TeV，角分辨率为 0.07−0.1°。我们检查了发射的不同部分的γ射线光谱，同时受益于我们的新数据提供的这些能量上前所未有的统计数据和角分辨率。我们还使用其他波长（如射电、X 射线、GeVγ 射线和 10 TeVγ 射线）的测量来精确模拟发射机制。结果我们检测到扩展的 γ 射线发射在空间上与 SNR G106.3+2.7 头部和尾部的射电连续谱发射一致。我们仅从尾部区域检测到能量高于 6.0 TeV 的显着 γ 射线发射，这一事实表明，通过空气喷淋实验（Milagro、HAWC、Tibet ASγ 和 LHAASO）检测到的高于 10 TeV 的发射仅从 SNR 尾部发射。在此假设下，头部区域的多波长谱可以用强子或轻子模型来解释，而尾部区域的轻子模型与10 TeV以上的发射和X射线相矛盾。相比之下，强子模型可以通过假设该区域的质子谱的截止能量约为 1 PeV 来再现尾部观测到的谱。这种中年信噪比（4−10 kyr）中的高能发射可以通过考虑过去从信噪比中逸出的质子与目前周围的致密气体相互作用的情况来解释。结论在信噪比G106.3+2.7中用MAGIC望远镜检测到的γ射线发射区域是扩展的，并且在空间上与射电连续谱形态一致。尾部区域发射的多波长光谱表明质子加速到~PeV，而头部区域的发射机制可能是强子或轻子。
ContextCertain types of supernova remnants (SNRs) in our Galaxy are assumed to be PeVatrons, capable of accelerating cosmic rays (CRs) to ~ PeV energies. However, conclusive observational evidence for this has not yet been found. The SNR G106.3+2.7, detected at 1–100 TeV energies by different γ-ray facilities, is one of the most promising PeVatron candidates. This SNR has a cometary shape, which can be divided into a head and a tail region with different physical conditions. However, in which region the 100 TeV emission is produced has not yet been identified because of the limited position accuracy and/or angular resolution of existing observational data. Additionally, it remains unclear as to whether the origin of the γ-ray emission is leptonic or hadronic.AimsWith the better angular resolution provided by new MAGIC data compared to earlierγ-ray datasets, we aim to reveal the acceleration site of PeV particles and the emission mechanism by resolving the SNR G106.3+2.7 with 0.1° resolution at TeV energies.MethodsWe observed the SNR G106.3+2.7 using the MAGIC telescopes for 121.7 h in total – after quality cuts – between May 2017 and August 2019. The analysis energy threshold is ~0.2 TeV, and the angular resolution is 0.07−0.1°. We examined theγ-ray spectra of different parts of the emission, whilst benefitting from the unprecedented statistics and angular resolution at these energies provided by our new data. We also used measurements at other wavelengths such as radio, X-rays, GeVγ-rays, and 10 TeVγ-rays to model the emission mechanism precisely.ResultsWe detect extended γ-ray emission spatially coincident with the radio continuum emission at the head and tail of SNR G106.3+2.7. The fact that we detect a significantγ-ray emission with energies above 6.0 TeV from only the tail region suggests that the emissions above 10 TeV detected with air shower experiments (Milagro, HAWC, Tibet ASγand LHAASO) are emitted only from the SNR tail. Under this assumption, the multi-wavelength spectrum of the head region can be explained with either hadronic or leptonic models, while the leptonic model for the tail region is in contradiction with the emission above 10 TeV and X-rays. In contrast, the hadronic model could reproduce the observed spectrum at the tail by assuming a proton spectrum with a cutoff energy of ~1 PeV for that region. Such high-energy emission in this middle-aged SNR (4−10 kyr) can be explained by considering a scenario where protons escaping from the SNR in the past interact with surrounding dense gases at present.ConclusionsTheγ-ray emission region detected with the MAGIC telescopes in the SNR G106.3+2.7 is extended and spatially coincident with the radio continuum morphology. The multi-wavelength spectrum of the emission from the tail region suggests proton acceleration up to ~PeV, while the emission mechanism of the head region could either be hadronic or leptonic.