论文标题
DBI非传统标量场场景中DM和DE扰动的增长
The growth of DM and DE perturbations in DBI non-canonical scalar field scenario
论文作者
论文摘要
我们研究了不同声速对狄拉克出生式污染（DBI）场景中的黑暗能量的影响。 DBI动作包含在$ k $ - 源模型的类别中，并且在描述弦理论中D-Branes的有效自由度方面具有重要作用。在DBI设置中，我们采用抗DE保姆（ADS）扭曲因子$ f（ϕ）= f_0 \，ϕ^{ - 4} $，并研究自我相互作用的四分之一电位$ v（ϕ）= λϕ^{4}/4 $。我们计算模型的有效音速的全部表达，并表明它可以在宇宙演化过程中随时间演化。此外，绝热的音速随着时间的推移而演变，这在某种程度上影响了背景动态。我们表明，有效的音速非常接近绝热音速。我们检查了可变声速对线性和非线性方案中扰动生长的影响。在线性方案中，我们采用伪牛顿形式主义，并表明暗能量抑制了低红移时扰动的生长。从研究中，我们的设置中的综合sachs-wolf（ISW）效应，我们看到该模型与一致性$λ$ CDM模型显现出一些偏差。在非线性方案中，我们遵循球形塌陷模型的方法，并计算线性过度密度，病毒过度密度，过度密度和折叠区域的膨胀速率。我们进一步计算我们环境中给定质量上方的光环对象的相对数量密度，并表明在高红移的高质量尾巴中，相对于$λ$ CDM模型的结构数量越来越大。
We study the effect of varying sound speed on clustering dark energy in the Dirac-Born-Infeld (DBI) scenario. The DBI action is included in the class of $k$-essence models, and it has an important role in describing the effective degrees of freedom of D-branes in the string theory. In the DBI setup, we take the anti-de Sitter (AdS) warp factor $f(ϕ)=f_0\, ϕ^{-4}$, and investigate the self-interacting quartic potential $V(ϕ)=λϕ^{4}/4$. We calculate the full expression of the effective sound speed for our model, and show that it can evolve with time during the cosmological evolution. Besides, the adiabatic sound speed evolves with time here, and this influences the background dynamics to some extent. We show that the effective sound speed is very close to the adiabatic sound speed. We examine the effect of the variable sound speed on growth of the perturbations in both the linear and non-linear regimes. In the linear regime, we apply the Pseudo-Newtonian formalism, and show that dark energy suppresses the growth of perturbations at low redshifts. From study the Integrated Sachs-Wolf (ISW) effect in our setup, we see that the model manifests some deviation from the concordance $Λ$CDM model. In the non-linear regime, we follow the approach of spherical collapse model, and calculate the linear overdensity, the virial overdensity, overdensity at the turn around and the rate of expansion of collapsed region. We further compute relative number density of halo objects above a given mass in our setting, and show that the number of structures with respect to the $Λ$CDM model is reduced more in the high mass tail at high redshifts.
