Estimating the power spectrum of a discrete cosmic momentum field with fast Fourier transform

来源 :天文和天体物理学研究 | 被引量 : 0次 | 上传用户:szhzm4158
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
Fast Fourier transform based estimators are formulated for measuring momentum power spectra,including the auto power spectra of the momentum,the momentum divergence,and the cross spectrum of density fluctuation and momentum divergence.Algorithms using the third order Bettle-Lemarie scaling function to assign discrete objects to regular grids for fast Fourier transform are proposed to clean alias effects.Numerical experiments prove that the implementation can achieve sub-percent precision till close to the Nyquist frequency.The impact of removing bulk flow on the estimation of momentum power spectra is derived theoretically and verified numerically.Subtracting bulk flow has little effects at large scales but might induce meaningful differences in nonlinear regime,and probably it is not necessary to subtract bulk flow for samples which peculiar velocities are exact or sufficiently accurate.Momentum power spectra of dark matter samples from N-body simulation are measured and discussed.As expected,the prediction of the one loop Eulerian perturbation theory agrees with simulation only slightly better than the linear theory at z = 0,but can be applied to higher redshift with improved accuracy.Measurements of simulation data and the one loop Eulerian theory both reveal that the momentum field contains strong rotational part,and there is a large stochastic component in the divergence of momentum which is not correlated with the density field.The three kinds of momentum power spectra have their own characteristics.
其他文献
2009年可能是拍卖行业恢复发展以来困难最多、形势最为复杂的一年。据中拍协日前召开的行业形势分析会分析,2008年,拍卖行业遭遇严峻的市场考验,经济危机的影响在2009年会继
随着高品质声源的出现,许多Hi—Fi爱好者已愈来愈重视对高性能音箱的追求。他们尝试着做出了形式各异的箱体,可以说是动了不少脑筋,费了不少功夫。做过封闭式、倒相式、迷宫
围绕着拍卖程序的起始如何计算以及在拍卖现场只有一个竞买人举牌应价如何处理的问题,本刊特邀中拍协法律咨询委员会专家做客《中国拍卖》,进行了集中解答问:首先《拍卖法》
Quasi-biennial Oscillations(QBOs)of the Sun have a significant meaning as a benchmark of solar cycle,not only for understanding the dynamo action but also in te
2008年,坚持发展,运行总体良好2008年,在客观形势空前不利,经营环境复杂多变的条件下,全年拍卖场次55129场,比2007年增加10735场,企业运营总体良好。但是,由于宏观市场环境
文章主要对PEG和GrEDTA作为绵羊瘤胃液相标记物进行了比较研究。文章选用4只成年萨福克羊,平均体重为42kg,装有永久性瘤胃痊管,对其进行液相标记物PEG和CrEDTA的配制和饲养管理,
本文主要研究了聚羧酸减水剂与松香皂类脱模剂的适应性问题,并分析了气泡形成的原因,通过在聚羧酸减水剂中加入功能助剂,有效地解决了模板表面刷废机油或者松香皂类脱模剂后
文中分析了环氧乙烷易燃易爆、自聚、有毒等性质,并从实验室环氧乙烷的储存、管件、管路系统以及其他辅助设备等实际选用条件下提出了设计安全措施和管理安全措施,如低温小体
文章采用反相高效液相色谱进行了聚甲基丙烯酸减水剂中甲基丙烯酸、甲基丙烯磺酸钠、2-丙烯酰胺基-2-甲基丙磺酸、甲氧基聚乙二醇甲基丙烯酸酯4种单体的定量检测.测定小分子
维生素B_6与人体健康密切相关,它影响到入体各大组织功能,协助组成细胞的原料一氨基酸的合成,调节神经传导,协助产生抗体抵抗感染,据国内外医学家与营养学家研究新发现。vB_