Fang Ke, Kerr Matthew, Blandford Roger, Fleischhack Henrike, Charles Eric
Department of Physics, Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin, Madison, Wisconsin 53706, USA.
Space Science Division, Naval Research Laboratory, Washington, D.C. 20375, USA.
Phys Rev Lett. 2022 Aug 12;129(7):071101. doi: 10.1103/PhysRevLett.129.071101.
The existence of a "knee" at energy ∼1 PeV in the cosmic-ray spectrum suggests the presence of Galactic PeV proton accelerators called "PeVatrons." Supernova remnant (SNR) G106.3+2.7 is a prime candidate for one of these. The recent detection of very high energy (0.1-100 TeV) gamma rays from G106.3+2.7 may be explained either by the decay of neutral pions or inverse Compton scattering by relativistic electrons. We report an analysis of 12 years of Fermi-LAT gamma-ray data that shows that the GeV-TeV gamma-ray spectrum is much harder and requires a different total electron energy than the radio and x-ray spectra, suggesting it has a distinct, hadronic origin. The nondetection of gamma rays below 10 GeV implies additional constraints on the relativistic electron spectrum. A hadronic interpretation of the observed gamma rays is strongly supported. This observation confirms the long-sought connection between Galactic PeVatrons and SNRs. Moreover, it suggests that G106.3+2.7 could be the brightest member of a new population of SNRs whose gamma-ray energy flux peaks at TeV energies. Such a population may contribute to the cosmic-ray knee and be revealed by future very high energy gamma-ray detectors.
宇宙射线能谱中在能量约1 PeV处存在一个“膝部”，这表明存在被称为“PeVatron”的银河系PeV质子加速器。超新星遗迹（SNR）G106.3+2.7是其中一个的主要候选者。最近从G106.3+2.7探测到的甚高能（0.1 - 100 TeV）伽马射线，可能是由中性π介子的衰变或相对论电子的逆康普顿散射来解释。我们报告了对12年费米大面积望远镜（Fermi-LAT）伽马射线数据的分析，结果表明GeV-TeV伽马射线能谱要硬得多，并且与射电和X射线能谱相比需要不同的总电子能量，这表明它有独特的强子起源。未探测到低于10 GeV的伽马射线对相对论电子能谱施加了额外的限制。观测到的伽马射线的强子解释得到了有力支持。这一观测结果证实了长期以来寻找的银河系PeVatron与超新星遗迹之间的联系。此外，这表明G106.3+2.7可能是一个新的超新星遗迹群体中最亮的成员，其伽马射线能量通量在TeV能量处达到峰值。这样一个群体可能对宇宙射线膝部有贡献，并将被未来的甚高能伽马射线探测器揭示出来。
