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arXiv 1002.4405astro-ph.CO
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标准再电离与暗物质模型的区别

Distinguishing standard reionization from dark matter models

Aravind Natarajan, Dominik J. Schwarz

摘要:

威尔金森微波各向异性探测器(WMAP)实验已经探测到$5.5 σ$水平的再电离,并报告了平均光学深度为$0.088 \pm 0.015$。大角度$EE$偏振功率谱是再电离的一个强有力的探测器,它现在(从WMAP的第一个五年数据开始)是$2\le l \le6$的宇宙方差限制。在这里,我们考虑部分再电离引起的WIMP暗物质湮灭,并计算预期的偏振功率谱。我们比较了暗物质模型与标准的2步再电离理论,并研究是否可以区分使用当前和未来的CMB观测模型。我们认为暗物质湮灭在中间红移($z<60$)由于晕,以及湮灭在较高的红移由于自由粒子。为了研究高红移暗物质湮灭对CMB功率谱的影响,必须考虑复合后剩余电子对电离历史的贡献。红移$z<60$处的暗物质晕影响$EE$功率谱中的低多极$l<20$,而高红移$z>100$处的自由粒子暗物质的湮灭主要影响多极$l>10$。

英文摘要:

The Wilkinson Microwave Anisotropy Probe (WMAP) experiment has detected reionization at the $5.5 σ$ level and has reported a mean optical depth of $0.088 \pm 0.015$. A powerful probe of reionization is the large-angle $EE$ polarization power spectrum, which is now (since the first five years of data from WMAP) cosmic variance limited for $2\le l \le6$. Here we consider partial reionization caused by WIMP dark matter annihilation, and calculate the expected polarization power spectrum. We compare the dark matter models with a standard 2-step reionization theory, and examine whether the models may be distinguished using current, and future CMB observations. We consider dark matter annihilation at intermediate redshifts ($z<60$) due to halos, as well as annihilation at higher redshifts due to free particles. In order to study the effect of high redshift dark matter annihilation on CMB power spectra, it is essential to include the contribution of residual electrons (left over from recombination) to the ionization history. Dark matter halos at redshifts $z<60$ influence the low multipoles $l<20$ in the $EE$ power spectrum, while the annihilation of free particle dark matter at high redshifts $z>100$ mainly affects multipoles $l>10$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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