宇宙再电离信号的频域探测及并合过程中的冲压效应对气体金属增丰的影响

发布时间：2018-05-02 02:45

本文选题：21cm信号 + 功率谱　；参考：《上海交通大学》2010年硕士论文

【摘要】： 我们通过对宇宙再电离信号的前景成分进行较为全面、精确的仿真,并尝试利用多项式拟合的方法进行前景去除,探讨了宇宙再电离信号在频域空间上的探测问题。此外,研究了星系群RGH 80中并合作用产生的冲压剥离效应对星系际介质金属增丰的作用。对于宇宙再电离时期发射的21cm信号的探测是了解当时宇宙演化的重要手段,其已成为天体物理学界备受关注的前沿课题。在本文中,我们介绍了21cm信号的产生机制、功率谱及信号的模拟。之后模拟了21cm信号探测中的前景和仪器噪声。对于前景,我们分别讨论了银河系、AGNs (FRIFRIIs,射电宁静AGNs及GPSCSSs)、star-forming galaxies及星系团的贡献。对于仪器噪声,我们用高斯白噪声进行模拟,并参考了21CMA和LOFAR的仪器参数。根据信号的模拟结果,我们尝试了前景的去除工作,结果发现这种二次多项式拟合的去除方法存在一定的风险性,有可能会将21cm信号的大尺度结构拟合到前景中去。然而,此方法在波数k 0.4 Mpc~(-1)的范围内可以准确地重构21cm信号的一维功率谱。本文第二部分内容是关于冲压剥离作用对星系际介质金属增丰贡献的研究。我们研究了星系群RGH 80的高质量Chandra ACIS数据,此群被发现存在一个臂状X射线特征。我们分别计算了其X射线气体的二维温度和丰度分布图像,并在丰度图上发现一个高丰度的弧状结构,此结构的金属丰度比周围区域的值高出0.3 Z。我们证实了其X射线图像上的臂状结构、丰度图上的高丰弧状结构及成员星系PGC 046529之间存在很强的空间相关性,并推测高丰结构的气体是PGC 046529受到由其运动而产生的冲压被剥离出来的星际介质遗迹。从而说明冲压剥离作用在星系群中也可以作为一种有效的金属增丰机制。
[Abstract]:Through the comprehensive and accurate simulation of the foreground components of the cosmic reionization signal and the attempt to remove the foreground by polynomial fitting, the detection of the cosmic reionization signal in the frequency domain is discussed. In addition, the effect of the stamping and stripping effect in RGH 80 on metal enrichment in intergalactic medium is studied. The detection of 21cm signals emitted during the cosmic reionization period is an important means to understand the evolution of the universe at that time, and it has become a frontier subject of great concern in the field of astrophysics. In this paper, we introduce the generation mechanism, power spectrum and signal simulation of 21cm signal. Then the prospect of 21cm signal detection and instrument noise are simulated. For the future, we discuss the contributions of AGNs FRIFRI Isa, radio quiet AGNs, GPSCSS star-forming galaxies and cluster of galaxies, respectively. For the instrument noise, we use Gao Si white noise to simulate, and refer to the instrument parameters of 21CMA and LOFAR. According to the simulation results, we try to remove the foreground. The results show that the removal method of quadratic polynomial fitting has some risk, and it is possible to fit the large-scale structure of 21cm signal into the foreground. However, this method can accurately reconstruct the one-dimensional power spectrum of 21cm signal in the range of k0.4 Mpc-1). The second part of this paper is about the contribution of stamping and stripping to intergalactic medium metal enrichment. We studied the high quality Chandra ACIS data of galaxy cluster RGH 80, which was found to have an arm X-ray feature. The two-dimensional temperature and abundance distribution images of the X-ray gas are calculated, and a high abundance arc structure is found on the abundance diagram. The metal abundance of the structure is 0.3 Z higher than that of the surrounding region. We have confirmed that there is a strong spatial correlation between the arm structure on the X-ray image, the Gao Feng arc structure on the abundance map and the member galaxy PGC 046529. It is speculated that the gas of Gao Feng structure is the remnant of interstellar media which PGC 046529 was stripped out by its motion. It is suggested that ramming and stripping can also be used as an effective mechanism for metal enrichment in galaxy clusters.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：P141

【相似文献】