Coupled quintessence
Coupled quintessence
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DOI：
10.1103/physrevd.62.043511
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发表时间：
2000-08-15
影响因子：
5
通讯作者：
Amendola, L
中科院分区：
文献类型：
--
作者：
Amendola, L
宇宙介质的一个新的组成部分，一个光标量场或“精髓”，最近被提出来解释宇宙加速与动力学宇宙常数。这样一个领域预计将明确耦合到普通物质，除非一些未知的对称性阻止it. I调查的耦合的精粹（CQ）模型的宇宙学后果，假设指数势和线性耦合。该模型与具有任意幂律势的Brans-Dicke拉格朗日函数共形等价。我评估的宇宙微波背景和星系分布的密度扰动，在目前和导出的耦合常数的界限，从观测数据的比较。CQ的一个新特征是在物质主导时代，标量场具有有限且几乎恒定的能量密度。这个时期，表示为φ MDE，是动力学相空间中的鞍点。的phi MDE是负责的几个差异，相对于未耦合的quintessence：多极谱的微波背景是倾斜在大角度，声峰被移位，其幅度被改变，和目前的8 Mpc/h的密度变化减少。假设Ω（m）=0.3，原始波动斜率n（s）=1，则当前数据将无量纲耦合常数限制为小于或等于0.1的β。
A new component of the cosmic medium, a light scalar field or "quintessence," has been proposed recently to explain cosmic acceleration with a dynamical cosmological constant. Such a field is expected to be coupled explicitly to ordinary matter, unless some unknown symmetry prevents it. I investigate the cosmological consequences of a coupled quintessence (CQ) model, assuming an exponential potential and a linear coupling. This model is conformally equivalent to Brans-Dicke Lagrangians with any power-law potential. I evaluate the density perturbations on the cosmic microwave background and on the galaxy distribution at the present and derive bounds on the coupling constant from the comparison with observational data. A novel feature of CQ is that during the matter dominated era the scalar field has a finite and almost constant energy density. This epoch, denoted as phi MDE, is a saddle point in the dynamical phase space. The phi MDE is responsible of several differences with respect to uncoupled quintessence: the multipole spectrum of the microwave background is tilted at large angles, the acoustic peaks are shifted, their amplitude is changed, and the present 8 Mpc/h density variance is diminished. The present data constrain the dimensionless coupling constant to \beta\less than or equal to 0.1 assuming Omega(m)=0.3 and a primordial fluctuation slope n(s)=1.