Glimpse of the highly obscured HMXB IGR J16318-4848 with Hitomi
Glimpse of the highly obscured HMXB IGR J16318-4848 with Hitomi
复制标题
与 Hitomi 一起瞥见高度模糊的 HMXB IGR J16318-4848
DOI：
10.1093/pasj/psx154
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发表时间：
2018
影响因子：
2.3
通讯作者：
A. Bamba et al.
中科院分区：
文献类型：
--
作者：
Hitomi Collaboration;A. Bamba et al.
我们报告了对IGR J16318−4848的Hitomi观测，IGR J16318−4848是一个高质量X射线双星系统，具有极强的NH <$1024 cm −2吸收。以前的X射线研究表明，它的光谱主要是由铁的强荧光线以及连续发射线。为了深入了解后处理材料的物理和几何性质，我们利用了X射线微量热计（软X射线光谱仪：SXS）的高光谱分辨率和Hitomi上的软X射线成像仪和硬X射线成像仪（SXI和HXI）的宽波段灵敏度。尽管由于非预期的离轴指向而限制了光子计数，但是SXS光谱解析了Fe Kα 1和Kα 2线，并对线质心和线宽施加了强约束。谱线宽度对应于160 km s−1的速度。这代表了迄今为止从任何X射线双星中对这条线进行的最精确和最小的宽度测量，远小于类似系统的速度特征所预期的多普勒展宽和多普勒频移。结合SXI和HXI谱测量的K壳层边能，估计Fe的电离态在Fei-iv范围内。考虑到电离参数的估计和X射线源与吸收体之间的距离，估计的材料的密度和厚度。已经证实了非常强的吸收和康普顿肩关节组件的缺失。这些特征表明，对分布在窄立体角或散射中的材料进行再处理，主要是通过热自由电子或中性氢。该测量使用19个光子的SXS检测来实现。它为使用X射线天体物理学回收使命和其他类似的未来仪器对该双星和其他X射线双星进行后续观测提供了强大的动力。
We report on a Hitomi observation of IGR J16318−4848, a high-mass X-ray binary system with an extremely strong absorption ofNH∼ 1024cm−2. Previous X-ray studies revealed that its spectrum is dominated by strong fluorescence lines of Fe as well as continuum emission lines. For physical and geometrical insight into the nature of the reprocessing material, we utilized the high spectroscopic resolving power of the X-ray microcalorimeter (the soft X-ray spectrometer: SXS) and the wide-band sensitivity by the soft and hard X-ray imagers (SXI and HXI) aboard Hitomi. Even though the photon counts are limited due to unintended off-axis pointing, the SXS spectrum resolves Fe Kα1and Kα2lines and puts strong constraints on the line centroid and line width. The line width corresponds to a velocity of 160km s−1. This represents the most accurate, and smallest, width measurement of this line made so far from the any X-ray binary, much less than the Doppler broadening and Doppler shift expected from speeds that are characteristic of similar systems. Combined with the K-shell edge energy measured by the SXI and HXI spectra, the ionization state of Fe is estimated to be in the range of Fei–iv. Considering the estimated ionization parameter and the distance between the X-ray source and the absorber, the density and thickness of the materials are estimated. The extraordinarily strong absorption and the absence of a Compton shoulder component have been confirmed. These characteristics suggest reprocessing materials that are distributed in a narrow solid angle or scattering, primarily by warm free electrons or neutral hydrogen. This measurement was achieved using the SXS detection of 19 photons. It provides strong motivation for follow-up observations of this and other X-ray binaries using the X-ray Astrophysics Recovery Mission and other comparable future instruments.