Charge Exchange X-Ray Emission due to Highly Charged Ion Collisions with H, He, and H2: Line Ratios for Heliospheric and Interstellar Applications
Charge Exchange X-Ray Emission due to Highly Charged Ion Collisions with H, He, and H2: Line Ratios for Heliospheric and Interstellar Applications
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DOI：
10.3847/1538-4357/aa99d8
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发表时间：
2018-01-01
影响因子：
4.9
通讯作者：
Stancil, P. C.
中科院分区：
文献类型：
--
作者：
Cumbee, R. S.;Mullen, P. D.;Stancil, P. C.
电荷交换的基本碰撞过程（CX）已被确定为来自日球层、行星外球层和超新星残骸的x射线发射的主要来源。在这一过程中，x射线发射是由中性原子或分子的高电荷离子捕获电子，形成高激发、高电荷态离子而产生的。当被捕获的电子级联到最低能级时，光子被发射出来，包括x射线。为了提供可靠的CX诱导x射线光谱模型来真实地模拟这些环境，使用多通道朗道-齐纳、原子-轨道紧密耦合、分子-轨道紧密耦合和经典轨迹蒙特卡罗方法获得的理论CX横截面计算线比和光谱。计算了裸态和类H态C - Al离子与H、He和H-2碰撞的x射线光谱，并与实验数据进行了比较。利用这些谱线比，给出了天鹅座环超新星遗迹东北缘和日球层的CX发射的XSPEC模型，作为离子速度依赖的例子。
The fundamental collisional process of charge exchange (CX) has been established as a primary source of X-ray emission from the heliosphere, planetary exospheres, and supernova remnants. In this process, X-ray emission results from the capture of an electron by a highly charged ion from a neutral atom or molecule, to form a highly excited, high-charge state ion. As the captured electron cascades down to the lowest energy level, photons are emitted, including X-rays. To provide reliable CX-induced X-ray spectral models to realistically simulate these environments, line ratios and spectra are computed using theoretical CX cross sections obtained with the multichannel Landau-Zener, atomic-orbital close-coupling, molecular-orbital close-coupling, and classical trajectory Monte Carlo methods for various collisional velocities relevant to astrophysics. X-ray spectra were computed for collisions of bare and H-like C to Al ions with H, He, and H-2 with results compared to available experimental data. Using these line ratios, XSPEC models of CX emission in the northeast rim of the Cygnus Loop supernova remnant and the heliosphere are shown as examples with ion velocity dependence.