On the detectability of turbulence and bulk flows in X-ray clusters
On the detectability of turbulence and bulk flows in X-ray clusters
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关于 X 射线簇中湍流和整体流的可探测性
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
G. Bryan
中科院分区：
文献类型：
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作者：
R. Sunyaev;M. Norman;G. Bryan
冷却流动、星团合并以及星系通过超音速和音速星系团气体的运动必然导致星系团内介质(ICM)的大尺度运动。1999年诺曼和布莱恩对X射线星系团形成的高分辨率数值模拟预测了星系团范围内的湍流，包括νTurb≈300-600 km S∓1和涡度尺度≈100-500kpc，数值较大的是维里半径附近的湍流，而数值较小的是核心的湍流。模拟还预测了在几百kpc的尺度上，v≈为400kM的S−1的核心中将存在有序的整体流动。在本文中，我们考虑了这种流体运动的可观测性，通过它们通过运动学SZ效应在CMB中引起的扭曲，以及通过多普勒加宽和X射线谱中金属谱线的移位。我们估计|ΔT/T|运动学和lt；几个×10−6-在或低于当前的可检测极限。然而，我们发现，几个eV的能量分辨率足以探测到星系团核心6.7keV铁线中的几个多普勒频移分量。
Coolingflows, cluster mergers, and the motions of galaxies through cluster gas with supersonic and sonic velocities must lead to large scale motions of the intracluster medium (ICM). A high-resolution numerical simulation of X-ray cluster formation by Norman and Bryan (1999) predicts cluster-wide turbulence with νturb ≈300–600 km s∓1 and eddy scales louter ≈100–500 kpc, the larger numbers being characteristic of turbulence near the virial radius, while the smaller numbers pertain to the core. The simulation also predicts the existence of ordered bulk flows in the core with v≈400 km s−1 on scales of several hundred kpc. In this paper, we consider the observability of such fluid motions via the distortions they induce in the CMB via the kinematic SZ effect, as well as via Doppler broadening and shifting of metal lines in the X-ray spectrum. We estimate |ΔT/T|kinematic<few×10−6—at or below current limits of detectability. However, we find that an energy resolution of a few eV is sufficient to detect several Doppler shifted components in the 6.7 keV Fe line in the cluster core.