通过拓扑分析区分冷暗物质与自相互作用暗物质
Distinguishing cold and self-interacting dark matter through topological analysis
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中文总结 AI 辅助
该研究利用属统计量分析Darkium宇宙学模拟数据，发现密度场拓扑特征对暗物质自相互作用敏感，可作为区分自相互作用暗物质与冷暗物质的观测探针。
中文摘要 AI 辅助
为解决无碰撞冷暗物质（CDM）模型在星系尺度（≤1Mpc）预测面临的挑战，已出现多种替代暗物质（DM）模型。但在这类小尺度上，替代模型与CDM的区分因重子物理的简并性而困难，因此需采用不受重子影响的DM探针，例如处于星系尺度之上、模型收敛至CDM尺度之下的中间尺度。我们首次利用表征密度场拓扑结构的度量——属统计量（genus statistic），将自相互作用暗物质（SIDM）与CDM区分开来。我们基于Darkium仅含暗物质的宇宙学模拟开展分析，采用1种CDM模型和4种具有不同振幅及速度依赖关系的SIDM模型，对质量范围为10¹²至10¹⁴M⊙/h、红移z=0至z=2的数百个星系晕，计算其中心3个 virial 半径宽的选定区域的属统计量。我们还探索了更接近观测的配置：由于红移误差会阻碍密度场的三维重建，仅通过厚二维投影中的星系晕分布来追踪DM密度场。结果发现，对于z=0时质量大于10¹²M⊙/h的星系晕，在0.05Mpc/h范围内，CDM的密度场系统上比SIDM模型更团块状。这些预测表明，密度场的属统计量对DM自相互作用敏感，提示拓扑分析可作为区分观测到的星系晕分布中SIDM与CDM的有价值探针。
英文摘要
Alternative dark matter (DM) models have emerged to solve the challenges faced by the predictions of collisionless cold dark matter (CDM) on galactic scales ($\lesssim 1$ Mpc). However, disentangling alternative models from CDM is difficult on such small scales because of the degeneracy with baryonic physics. It is therefore necessary to use DM probes that are not affected by baryons, e.g. that stand on intermediate scales, larger than galactic while remaining smaller than the scale at which the models converge to CDM. For the first time, we distinguish self-interacting DM (SIDM) from CDM using the genus statistic, a metric that characterises the topology of the density field. We carried out the analysis on the Darkium DM-only cosmological simulations, using one CDM model and four SIDM models with cross-sections of various amplitudes and velocity dependencies. We computed the genus on selected 3-virial radius wide regions centred around halos, for few hundred halos with masses ranging from $10^{12}$ to $10^{14}$ M$_\odot/h$ over redshifts $z=0$ to $z=2$. We also explored a more observation-like configuration, where the DM density field is traced only from the halo distribution in thick 2D projection since in principle redshift errors hinder a 3D reconstruction of the density field. We find that the density field is systematically clumpier in CDM than in SIDM models up to $0.05~\mathrm{Mpc}/h$, for halos of masses larger than $10^{12}$ M$_\odot/h$ at $z=0$. These predictions show that the genus of the density field is sensitive to DM self-interactions, suggesting that topological analysis could provide a valuable probe for distinguishing SIDM from CDM in observed halo distributions.
