两百万个X射线源，以及一个不符合预期的簇群空间探测器

eROSITA望远镜发布了其覆盖半个天空的第二版X射线天空目录，包含近两百万个天体源。波恩的研究团队通过分析其中一个大质量星系簇群空间探测器的外围区域，发现该区域的气体温度、密度及重元素丰度均与现有模型预测不符。

The eROSITA telescope has released its second great catalogue of the X-ray sky with close to two million sources across half the sky, roughly double what it published before. Buried in it is a result from Bonn that matters more than the headline number. A team there went after the faintest part of a massive galaxy cluster, the outer region where fresh material is still arriving along threads of gas stretching between clusters. Nobody had measured that emission before. The gas turns out to be hotter, denser and poorer in heavy elements than the models say it should be.