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arXiv 1003.0884astro-ph.SRastro-ph.HE
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X射线太阳耀斑源的位置和大小

Positions and sizes of X-ray solar flare sources

E. P. Kontar, N. L. S. Jeffrey

摘要:

本文研究了X射线太阳耀斑源的位置和大小,并考虑了康普顿背散射。利用蒙特卡罗模拟模拟了X射线光子输运过程,包括光电吸收和康普顿散射,计算了不同源尺寸、光谱指数和主源方向性时太阳圆面上X射线源的视源尺寸和位置。我们表明,EQUIPDO效应将改变真实的源的位置,并大大增加了测量源的大小。源的位置被转移到$\sim 0.5"$径向朝向磁盘中心和5弧秒源的大小可以是两倍大,即使是各向同性源(最小的双折射效应)在1微米以上的光球。因此,X射线源应具有最小观测尺寸,因此,对于光球上方1 μ m高度处的盘中心点源($\sim 1.4"$),FWHM源尺寸(2.35倍二阶矩)将与20-50 keV范围内的$\sim 7"$一样大。源的大小和位置的变化是最大的平坦的主要X射线光谱,较强的向下各向异性,源更接近太阳盘中心,和之间的能量为30和50千电子伏。当解释来自RHESSI或Yohkoh数据的X射线足点位置、足点运动或源大小时,应考虑反照率,并建议足点源在X射线中应大于在光学或EUV范围中。

英文摘要:

We investigate the positions and source sizes of X-ray solar flare sources taking into account Compton backscattering (albedo). Using a Monte Carlo simulation of X-ray photon transport including photo-electric absorption and Compton scattering, we calculate the apparent source sizes and positions of X-ray sources at the solar disk for various source sizes, spectral indices and directivities of the primary source. We show that the albedo effect will alter the true source positions and substantially increase the measured source sizes. The source positions are shifted up to $\sim 0.5"$ radially towards the disk centre and 5 arcsecond source sizes can be two times larger even for an isotropic source (minimum albedo effect) at 1 Mm above the photosphere. X-ray sources therefore should have minimum observed sizes, thus FWHM source size (2.35 times second-moment) will be as large as $\sim 7"$ in the 20-50 keV range for a disk-centered point source at a height of 1 Mm ($\sim 1.4"$) above the photosphere. The source size and position change is the largest for flatter primary X-ray spectra, stronger downward anisotropy, for sources closer to the solar disk centre, and between the energies of 30 and 50 keV. Albedo should be taken into account when X-ray footpoint positions, footpoint motions or source sizes from e.g. RHESSI or Yohkoh data are interpreted, and suggest that footpoint sources should be larger in X-rays than in optical or EUV ranges.

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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