Substructure and merger detection in resolved NIKA Sunyaev-Zel'dovich images of distant clusters
Substructure and merger detection in resolved NIKA Sunyaev-Zel'dovich images of distant clusters
复制标题
遥远星团解析 NIKA Sunyaev-Zeldovich 图像中的子结构和合并检测
DOI：
10.1051/0004-6361/201731950
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发表时间：
2018
影响因子：
6.5
通讯作者：
Adam R
中科院分区：
文献类型：
--
作者：
Adam R
星系团热气层的亚结构与其形成历史和团内介质（ICM）中的天体物理过程有关。热Sunyaev-Zel'dovich（tSZ）效应直接敏感的视线集成ICM压力，因此特别适合于研究ICM子结构。在本文中，我们将结构增强滤波算法应用于高分辨率tSZ观测（例如，NIKA）的遥远的集群，以寻找压力不连续，压缩，并在ICM的第二个高峰。相同的过滤器被应用到玩具模型图像和合成的tSZ图像提取的RHAPSODY-G宇宙流体动力学模拟，为了更好地解释提取的功能。我们还研究了通过过滤器的噪声传播和量化的影响系统的影响，如数据处理引起的文物和点源残差，后者被确定为主要的潜在污染物。在我们的六个NIKA观察到的集群中的三个中，我们确定了高信噪比的特征，这些特征显示了合并事件的明确证据。在MACS J0717.5+3745（z= 0.55）中，在东部、东南部和西部扇区观察到三个强压力梯度，并确定了压力分布中的两个主峰。在冷核星系团PSZ 1 G045.85+57.71（z= 0.61）中，没有tSZ致密结构，东南部有一个tSZ梯度脊。在红移最高的星系团CL J1226.9+3332（z= 0.89）中，我们探测到一个长度约为45弧秒（360千秒差距）的脊压力梯度，与西部地区的第二个压力峰有关。我们的研究结果表明，目前的tSZ设施，现在已经达到的角分辨率和灵敏度，允许探索的细节压力子结构的集群，即使在高红移。这就有可能量化的tSZ信号和质量的集群，这是很重要的，当使用tSZ集群来测试宇宙模型之间的关系的动力学状态的影响。这项工作也标志着第一个NIKA集群样本数据的发布。
Substructures in the hot gas atmosphere of galaxy clusters are related to their formation history and to the astrophysical processes at play in the intracluster medium (ICM). The thermal Sunyaev-Zel’dovich (tSZ) effect is directly sensitive to the line-of-sight integrated ICM pressure, and is thus particularly adapted to study ICM substructures. In this paper, we apply structure-enhancement filtering algorithms to high-resolution tSZ observations (e.g., NIKA) of distant clusters in order to search for pressure discontinuities, compressions, and secondary peaks in the ICM. The same filters are applied to toy-model images and to synthetic tSZ images extracted from RHAPSODY-G cosmological hydrodynamic simulations, in order to better interpret the extracted features. We also study the noise propagation through the filters and quantify the impact of systematic effects, such as data-processing-induced artifacts and point-source residuals, the latter being identified as the dominant potential contaminant. In three of our six NIKA-observed clusters we identify features at high signal-to-noise ratio that show clear evidence for merger events. In MACS J0717.5+3745 (z= 0.55), three strong pressure gradients are observed on the east, southeast, and west sectors, and two main peaks in the pressure distribution are identified. We observe a lack of tSZ compact structure in the cool-core cluster PSZ1 G045.85+57.71 (z= 0.61), and a tSZ gradient ridge dominates in the southeast. In the highest redshift cluster, CL J1226.9+3332 (z= 0.89), we detect a ridge pressure gradient of ~45 arcsec (360 kpc) in length associated with a secondary pressure peak in the west region. Our results show that current tSZ facilities have now reached the angular resolution and sensitivity to allow an exploration of the details of pressure substructures in clusters, even at high redshift. This opens the possibility to quantify the impact of the dynamical state on the relation between the tSZ signal and the mass of clusters, which is important when using tSZ clusters to test cosmological models. This work also marks the first NIKA cluster sample data release.