标题： 星系团中的重子分布作为氦核沉降的结果 显示英文标题

标题： Baryon Distribution in Galaxy Clusters as a Result of Sedimentation of Helium Nuclei

摘要： 根据玻尔兹曼分布，星团中的重粒子比轻粒子更倾向于集中在中心。 漂移速度的估计表明，在哈勃时间范围内氦核可能已经部分或完全沉积到星团核心。 我们利用NFW分布作为星团的暗物质分布，并假设星团气体是等温且处于流体静力平衡状态，展示了这一情景。 我们发现，分布在小半径处的重子物质比例大于大半径处，这挑战了普遍认为重子分数随着星团半径单调增加的说法。 结果表明，传统的使用X射线测量星团气体以及恒定平均分子量来估算质量的方法，可能低估了总质量达$\sim 20%$，从而导致高估了总重子分数同样百分比。 此外，指出氦核向星团核心沉积可能至少部分解释了一些星团中观测到的中央X射线发射尖峰现象。 显示英文摘要

摘要： Heavy particles in galaxy clusters tend to be more centrally concentrated than light ones according to the Boltzmann distribution. An estimate of the drift velocity suggests that it is possible that the helium nuclei may have entirely or partially sedimented into the cluster core within the Hubble time. We demonstrate the scenario using the NFW profile as the dark matter distribution of clusters and assuming that the intracluster gas is isothermal and in hydrostatic equilibrium. We find that a greater fraction of baryonic matter is distributed at small radii than at large radii, which challenges the prevailing claim that the baryon fraction increases monotonically with cluster radius. It shows that the conventional mass estimate using X-ray measurements of intracluster gas along with a constant mean molecular weight may have underestimated the total cluster mass by $\sim 20%$, which in turn leads to an overestimate of the total baryon fraction by the same percentage. Additionally, it is pointed out that the sedimentation of helium nuclei toward cluster cores may at least partially account for the sharp peaks in the central X-ray emissions observed in some clusters.