arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1008.2693astro-ph.CO
收藏

用于宇宙学探测的参数化标量张量理论

Parameterizing scalar-tensor theories for cosmological probes

Stephen A Appleby, Jochen Weller

摘要:

研究了一类与$Λ$ CDM背景宇宙学非常相似的$f(R)$模型的密度扰动演化.利用准静态近似,以及这些模型等价于标量-张量引力的事实,我们用标量场的质量$M$写出修正的弗里德曼和宇宙学扰动方程。利用微扰方程,我们导出了生长参数$γ$的$M$解析表达式,并利用我们的结果重建了线性物质的功率谱。我们发现,在$z \sim 0$的功率谱的特点是倾斜相对于其广义相对论的形式,在小尺度上的功率增加。我们将讨论如何修改标准的,恒定的$γ$处方,以研究这类模型的结构形成。由于$γ$现在是尺度和时间相关的,与线性物质功率谱相关的振幅和传递函数都将被修改。我们建议一个简单的参数化的标量场的质量,这使我们能够计算的物质功率谱的广泛的一类$f(R)$模型。

英文摘要:

We study the evolution of density perturbations for a class of $f(R)$ models which closely mimic $Λ$CDM background cosmology. Using the quasi-static approximation, and the fact that these models are equivalent to scalar-tensor gravity, we write the modified Friedmann and cosmological perturbation equations in terms of the mass $M$ of the scalar field. Using the perturbation equations, we then derive an analytic expression for the growth parameter $γ$ in terms of $M$, and use our result to reconstruct the linear matter power spectrum. We find that the power spectrum at $z \sim 0$ is characterized by a tilt relative to its General Relativistic form, with increased power on small scales. We discuss how one has to modify the standard, constant $γ$ prescription in order to study structure formation for this class of models. Since $γ$ is now scale and time dependent, both the amplitude and transfer function associated with the linear matter power spectrum will be modified. We suggest a simple parameterization for the mass of the scalar field, which allows us to calculate the matter power spectrum for a broad class of $f(R)$ models.

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。

↑