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arXiv 1402.5502astro-ph.CO
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符合CMB功率谱的中微子模型

A neutrino model fit to the CMB power spectrum

T. Shanks, R. W. F. Johnson, J. A. Schewtschenko, J. R. Whitbourn

摘要:

标准宇宙学模型LCDM对宇宙微波背景(CMB)数据有很好的拟合。然而,该模型具有众所周知的问题。例如,宇宙学常数被微调到10^100分之一,而冷暗物质(CDM)粒子在实验室中还没有被检测到。Shanks之前研究了一个既不假设奇异粒子也不假设宇宙学常数的模型,而是假设一个低的哈勃常数(H_0),以允许重子密度与暴胀和零空间曲率相容。然而,最近的普朗克结果使它更难调和这样的模型与CMB功率谱。在这里,我们放松了先前的假设,以评估假设三个质量约为5eV的活跃中微子的影响。如果我们假设H_0较低,约为45 kms ^-1 Mpc ^-1,那么与之前的纯重子模型相比,我们发现普朗克功率谱的前3个峰值的拟合度有了显著提高。尽管如此,拟合优度仍然显著差于LCDM,并且需要对未知的系统效应进行上诉,才能将拟合视为可接受。另一个严重的问题是,波动的幅度很低(σ_8 ~0.2),这使得到目前为止很难形成星系。这可能需要种子,也许是来自原始磁场的种子,被调用来形成星系形成。这些问题和其他问题表明了LCDM以外的模型在拟合更精确的宇宙学数据时所面临的困难。

英文摘要:

The standard cosmological model, LCDM, provides an excellent fit to Cosmic Microwave Background (CMB) data. However, the model has well known problems. For example, the cosmological constant, is fine-tuned to 1 part in 10^100 and the cold dark matter (CDM) particle is not yet detected in the laboratory. Shanks previously investigated a model which assumed neither exotic particles nor a cosmological constant but instead postulated a low Hubble constant (H_0) to allow a baryon density compatible with inflation and zero spatial curvature. However, recent Planck results make it more difficult to reconcile such a model with CMB power spectra. Here we relax the previous assumptions to assess the effects of assuming three active neutrinos of mass ~5eV. If we assume a low H_0~45kms^-1Mpc^-1 then, compared to the previous purely baryonic model, we find a significantly improved fit to the first 3 peaks of the Planck power spectrum. Nevertheless, the goodness-of-fit is still significantly worse than for LCDM and would require appeal to unknown systematic effects for the fit ever to be considered acceptable. A further serious problem is that the amplitude of fluctuations is low (sigma_8~0.2) making it difficult to form galaxies by the present day. This might then require seeds, perhaps from a primordial magnetic field, to be invoked for galaxy formation. These and other problems demonstrate the difficulties faced by models other than LCDM in fitting ever more precise cosmological data.

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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