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arXiv 1601.06323astro-ph.CO
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用普朗克方法对星系团的光谱成像

Spectral imaging of galaxy clusters with Planck

H. Bourdin, P. Mazzotta, E. Rasia

摘要:

Sunyaev-Zeldovich(SZ)效应是探测星系团外围热气体存在的一个很有前途的工具。我们开发了一种光谱成像算法,致力于与普朗克附近的星系团的SZ观测,其目的是揭示气体密度各向异性相关的物质的吸积,或压力不连续引起的冲击波阵面的传播。为了优化角分辨率和精度之间的SZ通量测量的不可避免的权衡,该算法进行了多尺度分析的SZ地图以及其他扩展组件,如宇宙微波背景(CMB)的各向异性和银河热尘埃。SZ信号的解混是通过核加权似然最大化处理的。CMB各向异性进一步分析,通过小波分析,而银河前景和SZ地图分析通过曲波分析,最好地保留其各向异性的细节。通过模拟普朗克高频仪器和指向天空中的几个特征位置获得的星系团的模拟观测的算法性能进行了测试。这些测试表明,普朗克应该很容易让我们检测到星系团外围的细丝,并检测到具有有利几何形状的碰撞星系团中的大规模冲击。

英文摘要:

The Sunyaev-Zeldovich (SZ) effect is a promising tool for detecting the presence of hot gas out to the galaxy cluster peripheries. We developed a spectral imaging algorithm dedicated to the SZ observations of nearby galaxy clusters with Planck, with the aim of revealing gas density anisotropies related to the filamentary accretion of materials, or pressure discontinuities induced by the propagation of shock fronts. To optimize an unavoidable trade-off between angular resolution and precision of the SZ flux measurements, the algorithm performs a multiscale analysis of the SZ maps as well as of other extended components, such as the cosmic microwave background (CMB) anisotropies and the Galactic thermal dust. The demixing of the SZ signal is tackled through kernel weighted likelihood maximizations. The CMB anisotropies are further analyzed through a wavelet analysis, while the Galactic foregrounds and SZ maps are analyzed via a curvelet analysis that best preserves their anisotropic details. The algorithm performance has been tested against mock observations of galaxy clusters obtained by simulating the Planck High Frequency Instrument and by pointing a few characteristic positions in the sky. These tests suggest that Planck should easily allow us to detect filaments in the cluster peripheries and detect large-scale shocks in colliding galaxy clusters that feature favorable geometry.

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