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Imprint of a Steep Equation of State in the growth of structure
Astroparticle Physics ( IF 3.5 ) Pub Date : 2020-02-01 , DOI: 10.1016/j.astropartphys.2019.102388
Mariana Jaber-Bravo , Erick Almaraz , Axel de la Macorra

We study the cosmological properties of a dynamical of dark energy (DE) component determined by a Steep Equation of State (SEoS) $w(z)=w_0+w_i\frac{(z/z_T)^q}{1+(z/z_T)^q}$. The SEoS has a transition at $z_T$ between two pivotal values ($w_i, w_0$) which can be taken as an early time and present day values of $w$ and the steepness is given by $q$. We describe the impact of this dynamical DE at background and perturbative level. The steepness of the transition has a better cosmological fit than a conventional CPL model with $w=w_0+w_a(1-a)$. Furthermore, we analyze the impact of steepness of the transition in the growth of matter perturbations and structure formation. This is manifest in the linear matter power spectrum, $P(k)$, the logarithmic growth function, $f\sigma_8(z)$, and the differential mass function $dn/d\log M(z=0)$. The differences in these last three quantities is at a percent-level using the same cosmological baseline parameters in our SEoS and a $\Lambda CDM$ model. However, we find an increase in the power spectrum, producing a bump at $k\approx k_T$ with $k_T\equiv a_TH(a_T)$ the mode associated to the time of the steep transition ($a_T = 1/(1+z_T)$). Different dynamics of DE lead to a different amount of DM at present time which has an impact in Power Spectrum and accordingly in structure formation.

中文翻译:

陡峭状态方程在结构增长中的印记

我们研究了由陡峭状态方程 (SEoS) $w(z)=w_0+w_i\frac{(z/z_T)^q}{1+(z /z_T)^q}$。SEoS 在两个关键值 ($w_i, w_0$) 之间的 $z_T$ 处有一个过渡,可以将其视为 $w$ 的早期和当前值,并且陡度由 $q$ 给出。我们描述了这种动态 DE 在背景和扰动水平上的影响。过渡的陡度比 $w=w_0+w_a(1-a)$ 的传统 CPL 模型具有更好的宇宙学拟合。此外,我们分析了过渡陡度对物质扰动增长和结构形成的影响。这体现在线性物质功率谱 $P(k)$、对数增长函数 $f\sigma_8(z)$ 和微分质量函数 $dn/d\log M(z=0)$ 中。在我们的 SEoS 和 $\Lambda CDM$ 模型中使用相同的宇宙学基线参数,这最后三个数量的差异处于百分比水平。然而,我们发现功率谱增加,在 $k\approx k_T$ 处产生一个凸起,$k_T\equiv a_TH(a_T)$ 是与陡峭过渡时间相关的模式 ($a_T = 1/(1+ z_T)$)。DE 的不同动力学导致目前不同数量的 DM,这对功率谱和结构形成产生影响。
更新日期:2020-02-01
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