Probing the Properties of the Pulsar Wind in the Gamma-Ray Binary HESS J0632+057 with NuSTAR and VERITAS Observations
Probing the Properties of the Pulsar Wind in the Gamma-Ray Binary HESS J0632+057 with NuSTAR and VERITAS Observations
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DOI：
10.3847/1538-4357/ab59de
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发表时间：
2019-11
期刊：
影响因子：
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通讯作者：
A. Archer;W. Benbow;R. Bird;A. Brill;R. Brose;M. Buchovecky;J. Christiansen;A. Chromey;W. Cu
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文献类型：
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作者：
A. Archer;W. Benbow;R. Bird;A. Brill;R. Brose;M. Buchovecky;J. Christiansen;A. Chromey;W. Cu
HESS J0632+057是一颗伽玛射线双星，由一颗致密天体组成，围绕Be星星运行，周期约为315天。广泛的X射线和TeV伽马射线观测揭示了一个特殊的光变曲线，包含两个峰值，由一个凹陷分开。我们介绍了在2017年11月和12月使用努斯塔和VERITAS同时观测硬X射线和TeV伽马射线的结果。这些观测结果对应于轨道相位0.22和0.3，其中通量向第一个光变曲线峰值上升。在X射线数据中观察到谱指数从1.77 ± 0.05到1.56 ± 0.05的显着变化。多波长光谱能量分布（SED）来自观测的解释轻子模型，其中紧凑的对象被假定为脉冲星和非热辐射是由高能电子加速恒星和脉冲星风之间的碰撞所形成的冲击发射。SED拟合的结果表明，我们的数据可以一致地描述在这种情况下，并允许我们估计的脉冲星风的磁化在冲击形成的位置。我们的结果所提供的脉冲星风磁化的约束是一致的，从其他系统获得的。
HESS J0632+057 is a gamma-ray binary composed of a compact object orbiting a Be star with a period of about 315 days. Extensive X-ray and TeV gamma-ray observations have revealed a peculiar light curve containing two peaks, separated by a dip. We present the results of simultaneous observations in hard X-rays with NuSTAR and in TeV gamma-rays with VERITAS, performed in 2017 November and December. These observations correspond to the orbital phases ϕ ≈ 0.22 and 0.3, where the fluxes are rising toward the first light-curve peak. A significant variation of the spectral index from 1.77 ± 0.05 to 1.56 ± 0.05 is observed in the X-ray data. The multiwavelength spectral energy distributions (SED) derived from the observations are interpreted in terms of a leptonic model, in which the compact object is assumed to be a pulsar and nonthermal radiation is emitted by high-energy electrons accelerated at the shock formed by the collision between the stellar and pulsar wind. The results of the SED fitting show that our data can be consistently described within this scenario, and allow us to estimate the magnetization of the pulsar wind at the location of the shock formation. The constraints on the pulsar wind magnetization provided by our results are shown to be consistent with those obtained from other systems.