论文标题

绝热压缩对暗物质光环和径向加速关系的影响

The Effect of Adiabatic Compression on Dark Matter Halos and the Radial Acceleration Relation

论文作者

Li, Pengfei, McGaugh, Stacy S., Lelli, Federico, Tian, Yong, Schombert, James M., Ko, Chung-Ming

论文摘要

我们使用半经验模型来研究冷暗物质(CDM)框架中的径向加速关系(RAR)。具体而言,我们构建了80个模型星系,涵盖了与SPARC数据库中观察到的星系相同的参数空间,并使用丰度匹配和Halo质量浓度关系将它们分配给暗物质晕。我们考虑了几种丰富的匹配关系,发现与运动数据相比,一些与运动学数据更好。我们计算了重子和它们的暗物质光环之间不可避免的重力相互作用,从而导致原始NFW光晕的总体压缩。在光晕压缩之前,高质量星系大约位于观察到的RAR上,而低质量的星系在小半径上由于DM尖端而显示出向上弯曲的“钩子”,这使得它们与观察到的关系有系统地偏离。光晕压缩后,最初的NFW光晕变得更加集中在小半径上,从而对旋转曲线做出了更大的贡献。这增加了总加速度,使所有模型星系都远离观察到的关系。这些系统的偏差表明,仅具有丰度匹配的CDM模型无法解释观察到的RAR。进一步的影响(例如,反馈)将需要用适量的光环膨胀来抵消压缩,即使在具有深度潜在孔的高质量星系中,通常预计这种影响可以忽略不计。

We use a semi-empirical model to investigate the radial acceleration relation (RAR) in a cold dark matter (CDM) framework. Specifically, we build 80 model galaxies covering the same parameter space as the observed galaxies in the SPARC database, assigning them to dark matter halos using abundance matching and halo mass-concentration relations. We consider several abundance matching relations, finding some to be a better match to the kinematic data than others. We compute the unavoidable gravitational interactions between baryons and their dark matter halos, leading to an overall compression of the original NFW halos. Before halo compression, high-mass galaxies approximately lie on the observed RAR whereas low-mass galaxies display up-bending "hooks" at small radii due to DM cusps, making them deviate systematically from the observed relation. After halo compression, the initial NFW halos become more concentrated at small radii, making larger contributions to rotation curves. This increases the total accelerations, moving all model galaxies away from the observed relation. These systematic deviations suggest that the CDM model with abundance matching alone cannot explain the observed RAR. Further effects (e.g., feedback) would need to counteract the compression with precisely the right amount of halo expansion, even in high mass galaxies with deep potential wells where such effects are generally predicted to be negligible.

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