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arXiv 2212.01403astro-ph.COastro-ph.GA
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自相互作用暗物质宇宙学中大质量星系的性质与可观测量

Properties and observables of massive galaxies in self-interacting dark matter cosmologies

Claudio Mastromarino, Giulia Despali, Lauro Moscardini, Andrew Robertson, Massimo Meneghetti, Matteo Maturi

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13 pages, 12 figures
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AI总结：

本研究通过流体动力学宇宙学模拟对比了CDM和SIDM模型，发现重子物质的引入显著减小了两者差异，且SIDM中暗物质比例随恒星质量增加下降更快，需分离星系内部暗物质与发光物质以有效约束自相互作用。

摘要：

我们使用流体动力学宇宙学模拟来测试大质量星系质量范围（$10^{12}M_{\odot}h^{-1}<M<10^{13.5}M_{\odot}h^{-1}$）内冷暗物质模型与自相互作用暗物质模型（CDM和SIDM）之间的差异。我们考虑了两种SIDM模型：一种具有恒定截面$σ/m_χ=1\mathrm{cm^2g^{-1}}$，另一种的截面具有速度依赖性。我们分析了晕密度分布和浓度，并比较了所有场景下纯暗物质模拟和流体动力学模拟的预测结果。我们计算了最佳拟合的Einasto分布，将所得参数与先前研究进行比较，并定义了最佳拟合的浓度-质量关系。我们发现，相对于纯暗物质情况，重子的引入减小了不同暗物质模型之间的差异。在SIDM流体动力学运行中，与CDM密度分布的偏差对质量的依赖性较弱：最巨大的系统（$M>10^{13}M_{\odot}h^{-1}$）显示出核心化分布，而质量较小的系统（$M<10^{12.5}M_{\odot}h^{-1}$）则具有更尖的分布。最后，通过考察暗物质比例和强引力透镜爱因斯坦半径的分布，我们将模拟预测与观测结果进行了比较。我们发现，在SIDM中，暗物质比例随着恒星质量的增加而下降的速度比在CDM中更快，导致在$M_{*}>10^{11}M_{\odot}$时比例更低，这是SIDM的显著特征。同时，从CDM和SIDM流体动力学运行中得出的爱因斯坦半径分布，与观测到的$M>10^{13}M_{\odot}h^{-1}$强透镜样本相当。我们得出结论，自相互作用与重子之间的相互作用可以大大减小该质量尺度下CDM和SIDM模型之间预期的差异，并且需要能够分离星系内部区域暗物质和发光物质的技术来约束自相互作用。

英文摘要：

We use hydrodynamical cosmological simulations to test the differences between cold and self-interacting dark matter models (CDM and SIDM) in the mass range of massive galaxies ($10^{12}M_{\odot}h^{-1}<M<10^{13.5}M_{\odot}h^{-1}$). We consider two SIDM models: one with constant cross section $σ/m_χ=1\mathrm{cm^2g^{-1}}$ and one where the cross section is velocity-dependent. We analyse the halo density profiles and concentrations, comparing the predictions of dark-matter-only and hydrodynamical simulations in all scenarios. We calculate the best-fit Einasto profiles and compare the resulting parameters with previous studies and define the best-fit concentration-mass relations. We find that the inclusion of baryons reduces the differences between different dark matter models with respect to the DM-only case. In SIDM hydro runs, deviations from the CDM density profiles weakly depend on mass: the most massive systems ($M>10^{13}M_{\odot}h^{-1}$) show cored profiles, while the least massive ones ($M<10^{12.5}M_{\odot}h^{-1}$) have cuspier profiles. Finally, we compare the predictions of our simulations to observational results, by looking at the dark matter fractions and the distribution of strong lensing Einstein radii. We find that in SIDM the DM-fractions decrease more rapidly with increasing stellar mass than in CDM, leading to lower fractions at $M_{*}>10^{11}M_{\odot}$, a distinctive signature of SIDM. At the same time, the distribution of Einstein radii, derived from both CDM and SIDM hydro runs, is comparable to observed samples of strong lenses with $M>10^{13}M_{\odot}h^{-1}$. We conclude that the interplay between self-interaction and baryons can greatly reduce the expected differences between CDM and SIDM models at this mass scale, and that techniques able to separate the dark and luminous mass in the inner regions of galaxies are needed to constrain self-interactions.

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