透過X-ray和可見光觀測測試星系團中的液態靜力平衡

Abstract

我們利用可見光和CHANDRA 的觀測來測試八個星系團中的液態靜力平衡。透過壓力比例的觀察，我們發現非熱平衡的壓力貢獻會隨著半徑變化。我們結論在星系團中的液態靜力平衡條件是不適當的。然而因為缺乏足夠的強重力效應觀測，我們並無法有足夠的能力去觀察非熱壓力在冷核和非冷核星系團之間的差別。再者透過結合強和弱重力效應的觀測，我們發現Abell 1689 和其他兩個星團的熱壓力貢獻並不相同，我們推論1689 並不是一個典型的平衡星系團。未來為了透過壓力貢獻比例要有更多研究成果，我們需要更多準確的觀測包跨強和弱重力觀測，還有更多廣義的星系團模型。

We test the hydrostatic equilibrium in galaxy clusters with studying CHANDRA X-ray observations and results of optical analysis of 8 relaxed clusters. We nd that the contribution of non-thermal pressures is considerable and varying with the distance to the clusters' centres by investigating the pressure ratio pro les. We conclude that the hydrostatic equilibrium assumption is not appropriate for determining clusters' mass accurately. However, because of the lack of accurate strong gravitational lensing studies, we are not able to probe whether there is a di erence of non-thermal pressure contribution at small radii between cool core (CC) and non-cool core (NCC) clusters. And we nd that Abell 1689 is not a typical relaxed cluster due to its pressure ratio pro le, which is very di erent to other 2 pressure ratio pro les derived with combined strong and weak lensing information. For future work on the distribution of non-thermal pressure contribution, we suggest that studying with more general models on combined strong and weak lensing is necessary.