Neutron-capture and 2.22 MeV emission in the atmosphere of the secondary of an X-ray binary
Neutron-capture and 2.22 MeV emission in the atmosphere of the secondary of an X-ray binary
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X 射线双星次级大气中的中子俘获和 2.22 MeV 发射
DOI：
10.1051/0004-6361:20011201
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发表时间：
2001
影响因子：
6.5
通讯作者：
N. Guessoum
中科院分区：
文献类型：
--
作者：
P. Jean;N. Guessoum
本文研究了X射线双星系统中子在次级星大气层中俘获产生的2.22MeV辐射，其中中子产生于致密的主星星周围的吸积盘中，并向各个方向辐射。我们考虑了几种吸积盘模型（ADAF，ADIOS，SLE，Uniform-Temperature）和各种参数（吸积率，致密天体的质量，次级星星的质量、温度和成分，两个天体之间的距离等）。中子速率由吸积盘中的核反应网络计算，这是由反应速率公式处理，考虑到每个吸积模型给出的结构方程。详细研究了中子在伴星星星大气中的过程，包括热化、弹性和非弹性散射、吸收、逃逸、衰变和质子俘获。2.22兆电子伏光子的辐射传输被单独处理，考虑到星星大气的成分和密度。考虑到源的距离、相对于双星系统框架的观测方向以及源的旋转，可以计算从地球可以检测到的2.22 MeV辐射的最终通量，因为这可以导致通量中可观测的周期性。我们产生的2.22兆电子伏的强度，以及频谱的线，旋转多普勒频移效应可以导致的变化，可测量的INTEGRAL的光谱仪（SPI）的频谱的相位图。
We consider the production of 2.22 MeV radiation resulting from the capture of neutrons in the atmo- sphere of the secondary in an X-ray binary system, where the neutrons are produced in the accretion disk around the compact primary star and radiated in all directions. We have considered several accretion disk models (ADAF, ADIOS, SLE, Uniform-Temperature) and a varity of parameters (accretion rate, mass of the compact object, mass, temperature and composition of the secondary star, distance between the two objects, etc.). The neutron rates are calculated by a network of nuclear reactions in the accretion disk, and this is handled by a reaction-rate formulation taking into account the structure equations given by each accretion model. The processes undergone by the neutrons in the atmosphere of the companion star are studied in great detail, including thermalization, elastic and inelastic scatterings, absorption, escape from the surface, decay, and capture by protons. The radiative transfer of the 2.22 MeV photons is treated separately, taking into consideration the composition and density of the star's atmosphere. The nal flux of the 2.22 MeV radiation that can be detected from earth is calculated tak- ing into account the distance to the source, the direction of observation with respect to the binary system frame, and the rotation of the source, as this can lead to an observable periodicity in the flux. We produce phasograms of the 2.22 MeV intensity as well as spectra of the line, where rotational Doppler shift eects can lead to changes in the spectra that are measurable by INTEGRAL's spectrometer (SPI).