自从中微子振荡实验证明中微子有质量,测量中微子质量就成为当前宇宙学重要的研究课题。有质量的中微子能够对宇宙的演化产生重要的影响,依靠这些宇宙学效应,高精度的天文观测可以提供很紧的中微子质量限制。基于ACDM模型,来自普朗克卫星的宇宙微波背景的温度和极化数据结合重子声学振荡观测测得的中微子质量为∑m〓<0.17 eV。ACDM模型,宇宙学标准模型,是与当前的宇宙学观测相一致的理论模型。然而,其他的暗能量理论模型也并没有被当前的观测所排除,仍具有很强的竞争力。最近,人们逐渐意识到暗能量性质会很大程度上影响中微子的宇宙学测量。基于该发现,本文将进一步探究暗能量是如何影响中微子称重的。 本文着重研究动力学暗能量宇宙中的中微子宇宙学称重问题。我们将利用最新的微波背景数据结合大尺度结构观测和低红移的几何测量,在动力学暗能量模型中开展中微子的宇宙学测量及中微子宇宙学效应的探究等工作。动力学暗能量模型是描述暗能量具有动力学演化特征的理论模型。本文选择的动力学暗能量模型有wCDM模型、 w〓w〓CDM模型、全息暗能量模型。除此之外,相互作用暗能量模型和修改引力模型也会在文中有所涉及。 首先,我们利用当前的天文观测对包含中微子质量的wCDM模型和w〓w〓CDM模型进行了宇宙学测量。中微子质量和暗能量的测量结果表明,相较于暗能量为常数情况,幽灵或早期幽灵(暗能量状态方程w有w<-1或w<-1到w>-1)支持一个较大上限的中微子质量。对于暗能量,当前的观测仍不支持其状态方程w有偏离-1的情况。其次,利用宇宙学观测对全息暗能量模型中的中微子质量进行宇宙学测量。结果表明,相较于暗能量为常数情况,早期精质类(暗能量状态方程w有w>-1到w<-1)的全息暗能量支持一个较小上限的中微子质量,上限只有∑m〓<0.113 eV。 继续探究相互作用暗能量模型和修改引力模型对中微子称重的影响。当考虑真空暗能量和暗物质相互作用时,相较于ACDM模型中的情况,Q=βHρ〓模型支持一个较大上限的中微子质量;Q=βHρ〓模型则支持一个与ΛCDM模型中的情况相一致的中微子质量。修改引力f(R)模型也支持一个与ΛCDM模型中的情况相一致的中微子质量。 除此之外,本文也讨论了有质量的中微子否能够对当前宇宙学观测的不一致性有所缓解。在全息暗能量模型中,用额外引入的惰性中微子参量去缓解哈勃常数的直接测量和Planck的间接测量之间的不一致性。从结果中发现,在全息暗能量和惰性中微子参量考虑下,H₀的拟合值变大,在某种程度上Planck和H₀的直接测量的不一致性得到缓解。然而,由于过多的自由参数被考虑在模型中,测量伴随了较大的统计误差。本文也在ΛCDM模型中引入(惰性或活性)中微子质量去缓解线性增长指数的测量和广义相对论预言之间的不一致性。从结果中发现,中微子质量的额外引入并没有对增长指数的测量结果产生重要的影响,因此该不一致性也不能得到缓解。 关键词:中微子质量;暗能量,动力学暗能量模型;宇宙学不一致性;增长指数
Since neutrino oscillation experiments proved that neutrinos have mass, measuring neutrino mass has become an important subject in cosmology. Massive neutrinos can have a significant impact on the evolution of the universe. Through these cosmological effects, high-precision astronomical observations can provide tight neutrino mass limits. The CMB temperature and polarization power spectra from Planck 2015 in combination with the baryon acoustic oscillations (BAO) data give a 95 per cent limit of ∑ m〓 < 0.17 eV based on the Λ cold dark matter (ΛCDM) model. The ΛCDM model, the cosmological standard model, is a theoretical model consistent with current cosmological observations. Other dark energy theoretical model, however, can not excluded by the current observation, still having very strong competitiveness. Recently, it has come to be realized that the dark energy properties can greatly influence the cosmological measurement of neutrinos. Based on this finding, this paper will explore further how dark energy affects neutrino weighing. This paper focuses on weighing neutrinos in dynamical dark energy cosmology. In this article, we will use the latest cosmic microwave background data combined with large-scale structure observations and low-redshift geometric measurements, to perform the cosmological measurement of the neutrino mass and explore cosmology effects of neutrinos in the dynamical dark energy model. The dynamical dark energy model describes that dark energy has the characteristic of dynamical evolution. This paper select dynamical dark energy models including the wCDM model, the w〓w〓 CDM model, and the holographic dark energy model. In addition, the interaction dark energy model and the modified gravity model are also involved in this paper. Firstly, we use current astronomical observations to make cosmological measurements for the ωCDM cosmology with the neutrino mass and the w〓w〓CDM model with the neutrino mass. The measurement results of neutrinos show that compared with the case of dark energy being constant, the cases of phantom and early phantom (ω has ω < -1 or ω< -1 to ω> -1 form) support a large upper limit of the neutrino mass. It is worth mentioning that, for the dark energy, current observations still do not support the state equation ω deviating from -1. Secondly, the neutrino mass in the holographic dark energy model was measured by cosmological observation. Results of the neutrino mass show that compared with the case of dark energy being constant, the case of early quintessence (ω has ω > -1 to ω < -1 form) of the holographic dark energy support a smaller limit of the neutrino mass, only up to∑〓<0.113 eV. Continuing considering the interacting dark energy model and the modified gravity model perforins a cosmological measurement of the neutrino mass. When considering vacuum dark energy interacting with dark matter, compared to the ΛCDM model, the Q = βH〓 model favors a larger upper limit of the neutrino mass; the Q = βH〓 model favor a consistent neutrino mass with the case of the ΛCDM model. The f(R) model also favors a consistent neutrino mass with the case of the ΛCDM model. In addition, this paper also discusses whether neutrinos can alleviate the current cosmological tensions. In the holographic dark energy model, using the extra induced sterile neutrino parameter to reconcile the tension between the Planck and the direct measurement of the Hubble constant, it was found that the fitting values of H₀ could become larger with the consideration of the holographic dark energy and the sterile neutrino, and thus this tension was relieved to some extent. However, the measurement is accompanied by a large statistical error because of too many free parameters considered in the model. The tension between the measurement of the growth index and the prediction of the general relativity is also discussed, when introducing (active/sterile) neutrino mass in cosmology. Prom the results, the extra introduction of the neutrino mass can not influence the measurement of the growth index, and thus the tension can not be reconciled well. Keywords: neutrino mass; dark energy; dynamical dark energy model; cosmological tension; growth index