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arXiv 1109.2767astro-ph.COgr-qchep-ph
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暗辐射的案例

The Case for Dark Radiation

Maria Archidiacono, Erminia Calabrese, Alessandro Melchiorri

摘要:

对最近宇宙学数据的综合分析显示了一个有趣的线索,即存在一个额外的相对论成分,即暗辐射。在这里,我们执行一个新的搜索暗辐射,参数化它的相对论自由度参数,$\neff$的有效数量。我们表明,我们考虑的宇宙学数据清楚地表明存在额外的相对论性成分与$\neff=4.08_{-0.68}^{+0.71}$在95% c.l.。对暗辐射声速$c_{\rm eff}$和粘度$c_{\rm vis}$参数进行分析,我们发现$\ceff=0.312\pm0.026$和$\cvis=0.29_{-0.16}^{+0.21}$在95% c.l.,与相对论性自由流动组分($\ceff=\cvis$ =1/3)的预期一致。假设存在3个相对论中微子,我们用$\nnus=1.10_{-0.72}^{+0.79}$和$\ceff=0.24_{-0.13}^{+0.08}$将额外的相对论分量限制在95% c. l.而$\cvis$结果为无约束。假设有大量的中微子成分,我们得到了$\nnus=1.12_{-0.74}^{+0.86}$在95% c.l.的暗辐射的进一步迹象。.

英文摘要:

Combined analyses of recent cosmological data are showing interesting hints for the presence of an extra relativistic component, coined Dark Radiation. Here we perform a new search for Dark Radiation, parametrizing it with an effective number of relativistic degrees of freedom parameter, $\neff$. We show that the cosmological data we considered are clearly suggesting the presence for an extra relativistic component with $\neff=4.08_{-0.68}^{+0.71}$ at 95% c.l.. Performing an analysis on Dark Radiation sound speed $c_{\rm eff}$ and viscosity $c_{\rm vis}$ parameters, we found $\ceff=0.312\pm0.026$ and $\cvis=0.29_{-0.16}^{+0.21}$ at 95% c.l., consistent with the expectations of a relativistic free streaming component ($\ceff=\cvis$=1/3). Assuming the presence of 3 relativistic neutrinos we constrain the extra relativistic component with $\nnus=1.10_{-0.72}^{+0.79}$ and $\ceff=0.24_{-0.13}^{+0.08}$ at 95% c.l. while $\cvis$ results as unconstrained. Assuming a massive neutrino component we obtain further indications for Dark Radiation with $\nnus=1.12_{-0.74}^{+0.86}$ at 95% c.l. .

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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