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arXiv 1409.0294astro-ph.CO
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减小BICEP2和普朗克测量之间的张力:参数空间的完整探索

Reducing the Tension Between the BICEP2 and the Planck Measurements: A Complete Exploration of the Parameter Space

Yi-Chao Li, Feng-Quan Wu, You-Jun Lu, Xue-Lei Chen

摘要:

BICEP 2团队基于他们的B模式偏振检测报告了一个大的暴胀张量标量比$r_\mathrm{0.002} = 0.20^{+0.07}_{-0.05}$,这超出了普朗克最佳拟合模型的$95\%$置信水平。我们探讨了几种可能的方法来减少两者之间的紧张关系,考虑一个模型,其中$α_\mathrm{s}$,$n_\mathrm{t}$,$n_\mathrm{s}$和中微子参数$N_\mathrm{eff}$和$Σm_\mathrmν$设置为自由参数。使用马尔可夫链蒙特卡罗(MCMC)技术调查完整的参数空间与BICEP 2的数据,我们发现,由此产生的约束$r_\mathrm{0.002}$是相互一致的,明显的紧张似乎是放松。对这些配件的进一步详细调查表明,$N_\mathrm{eff}$可能在降低张力方面起着最重要的作用。我们还发现,不采用一致性关系拟合得到的结果并没有偏离一致性关系太多。将现有的Planck、WMAP、BICEP 2和BAO数据集结合起来,得到$r_{0.002} = 0.14_{-0.11}^{+0.05}$、$n_\mathrm{t} = 0.35_{-0.47}^{+0.28}$、$n_\mathrm{s}=0.98_{-0.02}^{+0.02}$和$α_\mathrm{s}=-0.0086_{-0.0189}^{+0.0148}$ ;如果采用一致性关系,则得到$r_{0.002} = 0.22_{-0.06}^{+0.05}$。

英文摘要:

A large inflationary tensor-to-scalar ratio $r_\mathrm{0.002} = 0.20^{+0.07}_{-0.05}$ is reported by the BICEP2 team based on their B-mode polarization detection, which is outside of the $95\%$ confidence level of the Planck best fit model. We explore several possible ways to reduce the tension between the two by considering a model in which $α_\mathrm{s}$, $n_\mathrm{t}$, $n_\mathrm{s}$ and the neutrino parameters $N_\mathrm{eff}$ and $Σm_\mathrmν$ are set as free parameters. Using the Markov Chain Monte Carlo (MCMC) technique to survey the complete parameter space with and without the BICEP2 data, we find that the resulting constraints on $r_\mathrm{0.002}$ are consistent with each other and the apparent tension seems to be relaxed. Further detailed investigations on those fittings suggest that $N_\mathrm{eff}$ probably plays the most important role in reducing the tension. We also find that the results obtained from fitting without adopting the consistency relation do not deviate much from the consistency relation. With available Planck, WMAP, BICEP2 and BAO datasets all together, we obtain $r_{0.002} = 0.14_{-0.11}^{+0.05}$, $n_\mathrm{t} = 0.35_{-0.47}^{+0.28}$, $n_\mathrm{s}=0.98_{-0.02}^{+0.02}$, and $α_\mathrm{s}=-0.0086_{-0.0189}^{+0.0148}$; if the consistency relation is adopted, we get $r_{0.002} = 0.22_{-0.06}^{+0.05}$.

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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