Multiwavelength Investigation of Pulsar Wind Nebula DA 495 with HAWC, VERITAS, and NuSTAR
Multiwavelength Investigation of Pulsar Wind Nebula DA 495 with HAWC, VERITAS, and NuSTAR
复制标题
DOI：
10.3847/1538-4357/ab21d0
复制
发表时间：
2019-05
期刊：
影响因子：
--
通讯作者：
A. Coerver;P. Wilcox;H. Zhang;B. Dingus;E. Gotthelf;C. Hailey;T. Humensky;P. Kaaret;H. Li;K. Mori;R. Mukherjee;N. Park;H. Zhou
中科院分区：
文献类型：
--
作者：
A. Coerver;P. Wilcox;H. Zhang;B. Dingus;E. Gotthelf;C. Hailey;T. Humensky;P. Kaaret;H. Li;K. Mori;R. Mukherjee;N. Park;H. Zhou
2017年，高海拔水切伦科夫天文台在TeV伽马射线中探测到了脉冲星风星云DA 495(G65.7+1.2)(2HWC J1953+294)。高能辐射成像望远镜阵列系统的后续观测证实了2HWC J1953+294与DA 495之间的联系，并发现TeV辐射在空间上与1968年首次报告的射电辐射一致。来自DA495的TeV伽马射线的探测，以及过去高达10keV的X射线探测，促使作为NuSTAR银河遗产调查的一部分进行了高能X射线观测。我们给出了这些新星观测的结果，并结合钱德拉和XMM-牛顿的档案观测，证实了以前的Γ2-20keV的X射线光子指数=2.0±0.1。我们没有发现20keV以下的光谱截止值。随着DA495的光谱信息扩展到TeV伽马射线，我们能够执行分析建模来测试轻子和强子发射情景。轻子模型可以解释宽带辐射，但也暗示了一个弥漫X射线星云，其程度与射电星云和TeV星云相似，这一点无法得到我们的观测证实。强子模型可以同时解释所有波长的光谱和空间范围；然而，我们需要一个覆盖射电星云和TeV星云的非常高的磁场强度，以及令人惊讶的高粒子动能。这些要求加深了DA495的物理本质的奥秘。未来对射电到红外波段和空间分辨γ射线的观测可能会进一步限制DA495的物理条件和辐射机制。
Pulsar wind nebula DA 495 (G65.7+1.2) was detected in TeV gamma-rays by the High Altitude Water Cerenkov Observatory in 2017 (2HWC J1953+294). Follow-up observations by the Very Energetic Radiation Imaging Telescope Array System confirmed the association between 2HWC J1953+294 and DA 495 and found the TeV emission to be spatially coincident with the radio emission first reported in 1968. The detection of TeV gamma-rays from DA 495, along with past X-ray detection up to 10 keV, prompted high-energy X-ray observations as part of the NuSTAR Galactic Legacy Survey. We present the results of these NuSTAR observations, combined with archival Chandra and XMM-Newton observations, and confirm the previous X-ray photon index of Γ 2 – 20 keV = 2.0 ± 0.1 . We find no spectral cutoff up to 20 keV. With the spectral information for DA 495 extended to TeV gamma-rays, we were able to perform analytical modeling to test leptonic and hadronic emission scenarios. The leptonic models can explain the broadband emission, but also imply a diffuse X-ray nebula of similar extent to the radio and TeV nebulae, which cannot be confirmed by our observations. The hadronic models can simultaneously explain the spectrum and the spatial extent in all wavelengths; however, we need a very high magnetic field strength pervading the radio and TeV nebulae and a surprisingly high particle kinetic energy. These requirements deepen the mystery of the physical nature of DA 495. Future observations in radio to infrared bands and spatially resolved γ-rays can further constrain the physical conditions and radiation mechanisms in DA 495.