arXiv 1906.061332019-06astro-ph.GA

利用Milky Way的旋转曲线估算局域暗物质密度

On the estimation of the Local Dark Matter Density using the rotation curve of the Milky Way

P. F. de Salas, K. Malhan, K. Freese, K. Hattori, M. Valluri

备注：: 19 pages, 8 figures, 4 tables
发表信息：: JCAP 10 (2019) 037
DOI：: 10.1088/1475-7516/2019/10/037

摘要：

银河系的自转曲线常被用于估算局部暗物质密度$ρ_{{\rm DM},\odot}$。然而，估计是受选择的重子分布需要在这类研究。在这项工作中，我们探讨了几个银河系的质量模型，不同的重子和暗物质的分布，以确定$ρ_{{\rm DM},\odot}$。为此目的，我们分析银河系的精确圆速度曲线测量到$\sim 25$ kpc从银河系中心获得盖亚DR 2 [1]。我们发现，$ρ_{{\rm DM},\odot}$的估计值保持稳健的球形暗物质晕的合理变化。然而，我们表明，$ρ_{{\rm DM},\odot}$的基础重子组件的模型的选择的影响。特别是，我们发现，$ρ_{{\rm DM},\odot}$是最敏感的不确定性的磁盘组件的星系。我们还表明，当选择一个特定的重子模型，估计的$ρ_{{\rm DM},\odot}$只有约$10\%$的最佳拟合值的不确定性，但这种不确定性变得更大，当我们也考虑重子模型的变化。特别地，旋转曲线方法不允许排除额外的非常薄的组分的存在，其可以将$ρ_{{\rm DM},\odot}$增加超过8倍（薄盘甚至可以由暗物质制成）。因此，我们得出结论，专门使用银河系的旋转曲线是不够的，以提供一个强大的估计$ρ_{{\rm DM},\odot}$。对于所有的模型，我们研究没有一个额外的薄组件的存在下，我们得到的本地暗物质密度的估计值范围$ρ_{{\rm DM},\odot} \simeq \text{0.3--0.4}\,\mathrm{GeV/cm^3}$，与文献中的许多估计一致。

英文摘要：

The rotation curve of the Milky Way is commonly used to estimate the local dark matter density $ρ_{{\rm DM},\odot}$. However, the estimates are subject to the choice of the distribution of baryons needed in this type of studies. In this work we explore several Galactic mass models that differ in the distribution of baryons and dark matter, in order to determine $ρ_{{\rm DM},\odot}$. For this purpose we analyze the precise circular velocity curve measurement of the Milky Way up to $\sim 25$ kpc from the Galactic centre obtained from Gaia DR2 [1]. We find that the estimated value of $ρ_{{\rm DM},\odot}$ stays robust to reasonable changes in the spherical dark matter halo. However, we show that $ρ_{{\rm DM},\odot}$ is affected by the choice of the model for the underlying baryonic components. In particular, we find that $ρ_{{\rm DM},\odot}$ is mostly sensitive to uncertainties in the disk components of the Galaxy. We also show that, when choosing one particular baryonic model, the estimate of $ρ_{{\rm DM},\odot}$ has an uncertainty of only about $10\%$ of its best-fit value, but this uncertainty gets much bigger when we also consider the variation of the baryonic model. In particular, the rotation curve method does not allow to exclude the presence of an additional very thin component, that can increase $ρ_{{\rm DM},\odot}$ by more than a factor of 8 (the thin disk could even be made of dark matter). Therefore, we conclude that exclusively using the rotation curve of the Galaxy is not enough to provide a robust estimate of $ρ_{{\rm DM},\odot}$. For all the models that we study without the presence of an additional thin component, our resulting estimates of the local dark matter density take values in the range $ρ_{{\rm DM},\odot} \simeq \text{0.3--0.4}\,\mathrm{GeV/cm^3}$, consistent with many of the estimates in the literature.

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英文摘要：

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