Multiwavelength studies of G298.6?0.0: An old GeV supernova remnant interacting with molecular clouds
Multiwavelength studies of G298.6?0.0: An old GeV supernova remnant interacting with molecular clouds
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G298.6?0.0 的多波长研究：古老的 GeV 超新星遗迹与分子云相互作用
DOI：
10.1093/pasj/psad006
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发表时间：
2023
影响因子：
2.3
通讯作者：
Sano Hidetoshi
中科院分区：
文献类型：
--
作者：
Yeung Paul K H;Bamba Aya;Sano Hidetoshi
与超新星遗迹（SNRs）相关的强子γ射线源可以作为宇宙射线从SNRs逃逸的秒表，随着时间的推移，宇宙射线逐渐从最高能量的粒子发展到最低能量的粒子。在这项工作中，我们分析了13.7年的Fermi-LAT数据，以研究SNR G298.6−0.0区域内/周围的γ射线特征。通过γ射线空间分析，我们探测到三个点状成分。其中，Src-NE位于SNR壳的东部，Src-NW与SNR的西部边缘相邻。Src-NE和Src-NW在1.8 GeV附近或以下的能量处出现光谱断裂，表明SNR年龄大于10 kyr。我们还使用Chandra-ACIS数据研究了G298.6−0.0区域的X射线发射。我们检测到一个扩展的千电子伏源具有中心填充结构内的无线电壳。的X射线光谱很好地拟合的模型，假设碰撞电离平衡的热等离子体，进一步支持旧的SNR年龄。根据我们对南腾CO和ATCA-Parkes高线数据的分析，我们确定了从我们到G298.6−0.0的运动学距离为10.1 kpc。这一距离意味着SNR的物理半径很大，为15.5秒差距，这是年龄大于10 kyr的额外证据。除此之外，CO数据立方体使我们能够三维定位可能与SNR G298.6−0.0相互作用的分子云（MC），并可以解释在Src-NE或Src-NW检测到的强子γ射线。此外，多波长观测特性一致意味着SNR-MC相互作用主要发生在东北方向。
Hadronic γ-ray sources associated with supernova remnants (SNRs) can serve as stopwatches for the escape of cosmic rays from SNRs, which gradually develops from highest-energy particles to lowest-energy particles with time. In this work, we analyze the 13.7 yr Fermi-LAT data to investigate the γ-ray feature in/around the SNR G298.6−0.0 region. With γ-ray spatial analyses, we detect three point-like components. Among them, Src-NE is at the eastern SNR shell, and Src-NW is adjacent to the western edge of this SNR. Src-NE and Src-NW demonstrate spectral breaks at energies around/below 1.8 GeV, suggesting an old SNR age of >10 kyr. We also look into the X-ray emission from the G298.6−0.0 region, with the Chandra-ACIS data. We detected an extended keV source having a centrally filled structure inside the radio shell. The X-ray spectra are well fitted by a model which assumes a collisional ionization equilibrium of the thermal plasma, further supporting an old SNR age. Based on our analyses of the NANTEN CO- and ATCA-Parkes Hi-line data, we determined a kinematic distance of ∼10.1 kpc from us to G298.6−0.0. This distance entails a large physical radius of the SNR of ∼15.5 pc, which is additional evidence for an old age of >10 kyr. Besides this, the CO data cube enables us to three-dimensionally locate the molecular clouds (MCs) which are potentially interacting with SNR G298.6−0.0 and could account for the hadronic γ-rays detected at Src-NE or Src-NW. Furthermore, the multiwavelength observational properties unanimously imply that the SNR–MC interaction occurs mainly in the north-eastern direction.