arXiv 2009.057452020-09-12astro-ph.COgr-qchep-th

热暗物质结构形成的位力模式$k_v$方法

The virial mode $k_v$ approach to Structure Formation with Warm Dark Matter

Axel de la Macorra, Jorge Mastache

备注：: 15 pages, 4 figures

摘要：

小尺度结构为限制暗物质的动力学性质打开了一扇窗。在这里，我们研究了集群的暖暗物质（WDM）的半解析方法和比较的线性功率谱的WDM与冷暗物质（CDM）采用一个新的传递函数$T_v(a,k)$的病毒波数$k_v=2π/λ_v$对应的结构与病毒半径$r_v=λ_v/2$，一半的大小的自由流尺度半径$r_v=r_{fs}/2=λ_{fs}/4$。该结构中包含的维里质量$M_v$对应于WDM粒子形成的最轻结构，该WDM粒子在比例因子$a_{nr}$下变得非相对论性，并具有相应的$λ_{fs}$。病毒传递函数$T_v(a,k)=[1+ \left(k/k_v \right)^{β_v }]^{γ_v}$以病毒模式$k_v$和两个常数参数$β_v$和$γ_v$给出。我们比较$T_v(a,k)$与玻尔兹曼代码类WDM在1-10 keV的质量范围内，我们得到的约束$β_vγ_v=-18$与$ν=1.020 \pm 0.025$。在标准方法中，传递函数由$T(a,k)=[1+\left(α\, k \right)^β]^γ$ \cite{Viel:2005qj}给出，其中$α$编码WDM的动力学性质，并且必须借助于玻尔兹曼码进行数值调整。相比之下，在我们的病毒方法中，物理量$k_v$简单地根据自由流尺度$λ_{fs}$给出，并且可以通过分析确定。我们的病毒建议与CLASS有很好的一致性，并稍微改善了标准传递函数的结果。总之，我们提出了一个新的物理动机的传递函数$T_v(a,k)$，其中WDM的属性被编码在病毒波数$k_v$，是直接确定和提高WDM聚类属性的预测。

英文摘要：

The small scale structure opens a window to constrain the dynamical properties of Dark Matter. Here we study the clustering of warm dark matter (WDM) in a semi-analytical approach and compared the linear power spectrum of WDM with cold dark matter (CDM) employing a new transfer function $T_v(a,k)$ in terms of the viral wave number $k_v=2π/λ_v$ corresponding to a structure with a viral radius $r_v=λ_v/2$, half the size of the free streaming scale radius $r_v=r_{fs}/2=λ_{fs}/4$. The virial mass $M_v$ contained in this structure corresponds to the lightest structure formed for a WDM particle becoming non-relativistic at the scale factor $a_{nr}$ with the corresponding $λ_{fs}$. The viral transfer function $T_v(a,k)=[1+ \left(k/k_v \right)^{β_v }]^{γ_v}$ is given in terms of the viral mode $k_v$ and two constant parameters $β_v$ and $γ_v$. We compare $T_v(a,k)$ with the Boltzmann code CLASS for WDM in the mass range 1-10 keV and we obtain the constraint $β_vγ_v=-18$ with $ν=1.020 \pm 0.025$. In the standard approach the transfer function is given by $T(a,k)=[1+\left(α\, k \right)^β]^γ$ \cite{Viel:2005qj} where $α$ encodes the dynamical properties of WDM and must be numerically adjusted by means of a Boltzmann code. In contrast, in our viral approach the physical quantity $k_v$ is simply given in terms of the free streaming scale $λ_{fs}$ and can be analytically determined. Our viral proposal has a good agreement with CLASS and improves slightly the results from the standard transfer function. To conclude, we have proposed a new physically motivated transfer function $T_v(a,k)$ where the properties of WDM are encoded in the viral wave number $k_v$, is straightforward to determine and improves the prediction of WDM clustering properties.

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英文摘要：

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