Temperature map computation for X-ray clusters of galaxies
Temperature map computation for X-ray clusters of galaxies
复制标题
DOI：
10.1051/0004-6361:20031662
复制
发表时间：
2004-02
影响因子：
6.5
通讯作者：
H. Bourdin;J. Sauvageot;É. Slezak;A. Bijaoui;R. Teyssier
中科院分区：
文献类型：
--
作者：
H. Bourdin;J. Sauvageot;É. Slezak;A. Bijaoui;R. Teyssier
最近的数值模拟表明，星系团中气体温度的变化表明了这些星系团的动态状态。温度变化图显示了不同空间尺度上具有不同形状的复杂结构，例如热压缩区域、细丝、冷却流或大尺度温度分布。这里提出了一种新的多尺度光谱图像算法，用于恢复星系团内的空间温度变化。它专为与 XMM-Newton 卫星上的 EPIC MOS1、MOS2 和 PN 光谱成像仪配合使用而开发。将温度值拟合到包括源、宇宙 X 射线背景和宇宙射线诱发粒子背景的发射模型。使用 Haar 小波在小波空间中的不同尺度对空间温度变化进行编码，并通过对小波系数进行阈值处理来降噪。我们的局部温度估计器的行为渐进地类似于最佳最小方差界限估计器。但它对仪器和天体物理背景高度敏感，因此需要充分了解发射模型的每个组成部分。我们的算法已应用于 z = 0.1 处合并簇的模拟 60 ks 观测。结构形成 (AMR) 的 3D 流体动力学模拟提供了处于不同合并阶段的簇。多尺度方法使我们能够恢复合并子群核心内的微弱结构，其中气体发射率很高，但也恢复了其外部区域的大规模温度下降。
Recent numerical simulations have shown that the variations of the gas temperature in clusters of galaxies are in- dicative of the dynamical state of these clusters. Maps of the temperature variation show complex structures with different shapes at different spatial scales, such as hot compression regions, filaments, cooling flows, or large-scale temperature pro- files. A new multiscale spectro-imagery algorithm for restoring the spatial temperature variations within clusters of galaxies is presented here. It has been especially developed to work with the EPIC MOS1, MOS2 and PN spectro-imagers on board the XMM-Newton satellite. The temperature values are fitted to an emission model that includes the source, the cosmic X-ray background and cosmic-ray induced particle background. The spatial temperature variations are coded at different scales in the wavelet space using the Haar wavelet and denoised by thresholding the wavelet coefficients. Our local temperature estimator behaves asymptotically like an optimal mininum variance bound estimator. But it is highly sensitive to the instrumental and astrophysical backgrounds, so that a good knowledge of each component of the emission model is required. Our algorithm has been applied to a simulated 60 ks observation of a merging cluster at z = 0.1. The cluster at different stages of merging has been provided by 3-D hydrodynamical simulations of structure formation (AMR). The multiscale approach has enabled us to restore the faint structures within the core of the merging subgroups where the gas emissivity is high, but also the temperature decrease at large scale in their external regions.