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arXiv 1408.0174astro-ph.HE
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脉冲星风星云MSH ~15-52的高能X射线成像:粒子加速和输运的约束

High-Energy X-ray Imaging of the Pulsar Wind Nebula MSH~15-52: Constraints on Particle Acceleration and Transport

Hongjun An, Kristin K. Madsen, Stephen P. Reynolds, Victoria M. Kaspi, Fiona A. Harrison, Steven E. Boggs, Finn E. Christensen, William W. Craig, Chris L. Fryer… 展开作者

Hongjun An, Kristin K. Madsen, Stephen P. Reynolds, Victoria M. Kaspi, Fiona A. Harrison, Steven E. Boggs, Finn E. Christensen, William W. Craig, Chris L. Fryer, Brian W. Grefenstette, Charles J. Hailey, Kaya Mori, Daniel Stern, William W. Zhang

摘要:

我们提出了脉冲星风星云(PWN)MSH 15-52的硬X射线波段(>8千电子伏)的第一个图像,测量与核光谱望远镜阵列(NuSTAR)。总的来说,在3-7 keV波段的NuSTAR测量的PWN的形态与钱德拉高分辨率成像中看到的相似。然而,空间范围随着能量的增加而减小,我们将其归因于粒子远离激波时的同步能量损失。硬带图显示了相对赤字的计数在北部地区对RCW 89热残留物,具有显着的不对称性。我们发现,综合PWN光谱测量NuSTAR和钱德拉表明,有一个光谱断裂在6千电子伏,这可能是由一个中断的同步辐射发射电子分布在~200 TeV和/或不完善的交叉校准。我们还测量了空间分辨光谱,表明PWN的光谱软化远离中央脉冲星B1509-58,并存在一个大致正弦变化的光谱硬度在方位角方向。我们讨论了使用粒子流模型的结果。我们发现在喷流方向上移动的脉冲星的50”范围内,谱硬度随距离的变化具有非单调结构,这可能意味着粒子和磁场被磁环向应力压缩,正如以前对此源所提出的那样。我们还提出了2-D地图的光谱参数,并发现一个有趣的壳状结构的NH地图。我们讨论了壳状结构的可能起源及其影响。

英文摘要:

We present the first images of the pulsar wind nebula (PWN) MSH 15-52 in the hard X-ray band (>8 keV), as measured with the Nuclear Spectroscopic Telescope Array (NuSTAR). Overall, the morphology of the PWN as measured by NuSTAR in the 3-7 keV band is similar to that seen in Chandra high-resolution imaging. However, the spatial extent decreases with energy, which we attribute to synchrotron energy losses as the particles move away from the shock. The hard-band maps show a relative deficit of counts in the northern region towards the RCW 89 thermal remnant, with significant asymmetry. We find that the integrated PWN spectra measured with NuSTAR and Chandra suggest that there is a spectral break at 6 keV which may be explained by a break in the synchrotron-emitting electron distribution at ~200 TeV and/or imperfect cross calibration. We also measure spatially resolved spectra, showing that the spectrum of the PWN softens away from the central pulsar B1509-58, and that there exists a roughly sinusoidal variation of spectral hardness in the azimuthal direction. We discuss the results using particle flow models. We find non-monotonic structure in the variation with distance of spectral hardness within 50" of the pulsar moving in the jet direction, which may imply particle and magnetic-field compression by magnetic hoop stress as previously suggested for this source. We also present 2-D maps of spectral parameters and find an interesting shell-like structure in the NH map. We discuss possible origins of the shell-like structure and their implications.

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