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arXiv 0704.1603astro-ph
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利用PoGOLite中的康普顿散射测量软γ射线的能量相关极化

Measuring energy dependent polarization in soft gamma-rays using Compton scattering in PoGOLite

M. Axelsson, O. Engdegård, F. Ryde, S. Larsson, M. Pearce, L. Hjalmarsdotter, M. Kiss, C. Marini Bettolo, M. Arimoto, C-I. Björnsson, P. Carlson, Y. Fukazawa, T… 展开作者

M. Axelsson, O. Engdegård, F. Ryde, S. Larsson, M. Pearce, L. Hjalmarsdotter, M. Kiss, C. Marini Bettolo, M. Arimoto, C-I. Björnsson, P. Carlson, Y. Fukazawa, T. Kamae, Y. Kanai, J. Kataoka, N. Kawai, W. Klamra, G. Madejski, T. Mizuno, J. Ng, H. Tajima, T. Takahashi, T. Tanaka, M. Ueno, G. Varner, K. Yamamoto

摘要:

X射线和伽马射线的线偏振是许多天体物理学源的重要诊断,首先给出关于它们的几何形状、磁场和辐射机制的信息。然而,很少有X射线偏振测量,然后只有单能量的检测,而几个对象被假定为具有能量依赖的偏振签名。在本文中,我们调查是否有可能使用康普顿技术,特别是与拟议的PoGOLite气球实验,在25-100千电子伏的范围内,从宇宙源的能量依赖极化的检测。我们使用Geant 4模拟的PoGOLite模型和输入光子光谱的基础上天鹅座X-1和吸积磁天体(100 mCrab)。模拟了6小时和35小时的有效观测时间,分别对应于标准和长时间飞行。平滑和尖锐的能量变化的偏振进行了研究,并比较恒定的偏振信号,使用卡方统计。对于天鹅座X-1光谱(在硬态),如果反射分量被假设为完全偏振的,我们可以拒绝恒定的偏振和能量,而对于较弱的偏振则不能进行区分。对于吸积脉冲星,在偏振度至少为50%的窄能带中,可以拒绝恒定偏振,在偏振度为30%~ 0%的负阶跃分布中,也可以拒绝恒定偏振。

英文摘要:

Linear polarization in X- and gamma-rays is an important diagnostic of many astrophysical sources, foremost giving information about their geometry, magnetic fields, and radiation mechanisms. However, very few X-ray polarization measurements have been made, and then only mono-energetic detections, whilst several objects are assumed to have energy dependent polarization signatures. In this paper we investigate whether detection of energy dependent polarization from cosmic sources is possible using the Compton technique, in particular with the proposed PoGOLite balloon-experiment, in the 25-100 keV range. We use Geant4 simulations of a PoGOLite model and input photon spectra based on Cygnus X-1 and accreting magnetic pulsars (100 mCrab). Effective observing times of 6 and 35 hours were simulated, corresponding to a standard and a long duration flight respectively. Both smooth and sharp energy variations of the polarization are investigated and compared to constant polarization signals using chi-square statistics. We can reject constant polarization, with energy, for the Cygnus X-1 spectrum (in the hard state), if the reflected component is assumed to be completely polarized, whereas the distinction cannot be made for weaker polarization. For the accreting pulsar, constant polarization can be rejected in the case of polarization in a narrow energy band with at least 50% polarization, and similarly for a negative step distribution from 30% to 0% polarization.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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