arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1507.06646astro-ph.COgr-qchep-ph
收藏

超过六个参数:扩展$Λ$ CDM

Beyond six parameters: extending $Λ$CDM

Eleonora Di Valentino, Alessandro Melchiorri, Joseph Silk

摘要:

宇宙学约束通常是在一个$6$参数的假设下推导出来的,$Λ$ -CDM理论框架或简单的单参数扩展。在本文中,我们提出了,在一个显着扩展的情况下,宇宙学约束,同时变化到$12$宇宙学参数,包括中微子质量之和,中微子有效数,暗能量状态方程,引力波背景和运行的原始扰动谱指数。使用最新的普朗克2015年数据发布(偏振),我们没有发现扩展到标准$Λ$ -CDM情景的显著迹象,除了角功率谱透镜振幅,$A_{\rm lens}$大于预期值,超过两个标准差,即使将普朗克数据与BAO和Ia型超新星外部数据集结合起来。在我们扩展的宇宙学框架中,我们发现一个组合的普朗克+BAO分析约束的值的均方根。在$95 \%$ c.l.下的密度波动参数与$σ_8=0.781_{-0.063}^{+0.065}$,有助于缓解CFHTlenS宇宙剪切调查可能存在的紧张关系。我们还发现了一个较低的值为再电离光学深度$τ=0.058_{-0.043}^{+0.040}$在$95$ \% c.l.相对于在$Λ$ -CDM假设下导出的一个。标量光谱指数$n_S$现在与Harrison-Zeldovich光谱兼容,在$2.5$标准偏差内。将普朗克数据集与哈勃常数的HST先验结合起来,提供了状态方程$w < -1$的值,其标准偏差超过两个标准差,而中微子有效数与标准三中微子框架的期望完全兼容。

英文摘要:

Cosmological constraints are usually derived under the assumption of a $6$ parameters $Λ$-CDM theoretical framework or simple one-parameter extensions. In this paper we present, for the first time, cosmological constraints in a significantly extended scenario, varying up to $12$ cosmological parameters simultaneously, including the sum of neutrino masses, the neutrino effective number, the dark energy equation of state, the gravitational waves background and the running of the spectral index of primordial perturbations. Using the latest Planck 2015 data release (with polarization) we found no significant indication for extensions to the standard $Λ$-CDM scenario, with the notable exception of the angular power spectrum lensing amplitude, $A_{\rm lens}$ that is larger than the expected value at more than two standard deviations even when combining the Planck data with BAO and supernovae type Ia external datasets. In our extended cosmological framework, we find that a combined Planck+BAO analysis constrains the value of the r.m.s. density fluctuation parameter to $σ_8=0.781_{-0.063}^{+0.065}$ at $95 \%$ c.l., helping to relieve the possible tensions with the CFHTlenS cosmic shear survey. We also find a lower value for the reionization optical depth $τ=0.058_{-0.043}^{+0.040}$ at $95$ \% c.l. respect to the one derived under the assumption of $Λ$-CDM. The scalar spectral index $n_S$ is now compatible with a Harrison-Zeldovich spectrum to within $2.5$ standard deviations. Combining the Planck dataset with the HST prior on the Hubble constant provides a value for the equation of state $w < -1$ at more than two standard deviations while the neutrino effective number is fully compatible with the expectations of the standard three neutrino framework.

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。

↑