Gas thermodynamics meets galaxy kinematics: Joint mass measurements for eROSITA galaxy clusters,Astronomy & Astrophysics

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Gas thermodynamics meets galaxy kinematics: Joint mass measurements for eROSITA galaxy clusters
Astronomy & Astrophysics ( IF 5.4 ) Pub Date : 2024-12-17 , DOI: 10.1051/0004-6361/202451266
Pengfei Li, Ang Liu, Matthias Kluge, Johan Comparat, Yong Tian, Mariana P. Júlio, Marcel S. Pawlowski, Jeremy Sanders, Esra Bulbul, Axel Schwope, Vittorio Ghirardini, Xiaoyuan Zhang, Yunus Emre Bahar, Miriam E. Ramos-Ceja, Fabian Balzer, Christian Garrel

The mass of galaxy clusters is a critical quantity for probing cluster cosmology and testing theories of gravity, but its measurement could be biased, given that assumptions are inevitable in order to make use of any approach. In this paper, we employ and compare two mass proxies for galaxy clusters: thermodynamics of the intracluster medium and kinematics of member galaxies. We selected 22 galaxy clusters from the cluster catalog in the first SRG/eROSITA All-Sky Survey (eRASS1) that have sufficient optical and near-infrared observations. We generated multiband images in the energy range of (0.3, 7) keV for each cluster, and derived their temperature profiles, gas mass profiles, and hydrostatic mass profiles using a parametric approach that does not assume dark matter halo models. With spectroscopically confirmed member galaxies collected from multiple surveys, we numerically solved the spherical Jeans equation for their dynamical mass profiles. Our results quantify the correlation between dynamical mass and the line-of-sight velocity dispersion, log M_{dyn_{= (1.296 ± 0.001)log(σ_{los_{^{2^{r_{proj_{/G)−(3.87 ± 0.23), with a root mean square (rms) scatter of 0.14 dex. We find that the two mass proxies lead to roughly the same total mass, with no observed systematic bias. As such, the σ_{8_{tension is not specific to hydrostatic mass or weak lensing shears, but also appears with galaxy kinematics. Interestingly, the hydrostatic-to-dynamical mass ratios decrease slightly toward large radii, which could possibly be evidence for accreting galaxies in the outskirts. We also compared our hydrostatic masses with the latest weak lensing masses inferred with scaling relations. The comparison shows that the weak lensing mass is significantly higher than our hydrostatic mass by ∼110%. This might explain the significantly larger value of σ_{8_{from the latest measurement using eRASS1 clusters than almost all previous estimates in the literature. Finally, we tested the radial acceleration relation established in disk galaxies. We confirm the missing baryon problem in the inner region of galaxy clusters using three independent mass proxies for the first time. As ongoing and planned surveys are providing deeper X-ray observations and more galaxy spectra for cluster members, we expect to extend the study to cluster outskirts in the near future.}}}}}}}}}}}}

中文翻译：

气体热力学与星系运动学的结合：eROSITA 星系团的联合质量测量

星系团的质量是探测星系团宇宙学和测试引力理论的关键量，但考虑到使用任何方法的假设都是不可避免的，因此它的测量可能会有偏差。在本文中，我们采用并比较了星系团的两个质量代理：星系团内介质的热力学和成员星系的运动学。我们在第一次 SRG/eROSITA 全天空巡天（eRASS1）的星系表中选择了 22 个星系团，它们有足够的光学和近红外观测。我们为每个团簇生成了（0.3， 7） keV 能量范围内的多波段图像，并使用不假设暗物质晕模型的参数化方法推导出了它们的温度曲线、气体质量曲线和流体静力质量曲线。通过多次巡天收集的光谱证实的成员星系，我们数值求解了其动力学质量分布的球形 Jeans 方程。我们的结果量化了动态质量与视距速度色散之间的相关性，log Mdyn = （1.296 ± 0.001）log（σlos2rproj/G）−（3.87 ± 0.23），均方根（rms）散射为 0.14 dex。我们发现两个质量代理导致大致相同的总质量，没有观察到系统偏差。因此，σ8 张力并非特定于静水质量或弱透镜剪切，但也出现在星系运动学中。有趣的是，流体静力学质量比向大半径略微减小，这可能是郊区星系吸积的证据。我们还将静水质量与通过缩放关系推断的最新弱透镜质量进行了比较。比较表明，弱透镜质量明显比我们的静水质量高 ∼110%。这可能解释了为什么使用 eRASS1 集群的最新测量中 σ8 的值明显大于文献中几乎所有先前的估计值。最后，我们测试了在盘状星系中建立的径向加速度关系。我们首次使用三个独立的质量代理证实了星系团内部区域的重子缺失问题。由于正在进行的和计划中的巡天为星团成员提供了更深的X射线观测和更多的星系光谱，我们预计在不久的将来将研究扩展到星团的郊区。