RUI: Diffuse Emissions from Clusters and Superclusters of Galaxies

[摘要]丰富星系团形成的模型预测，星系初始质量的10%到70%已经被潮汐剥离，现在驻留在星系团内介质中。被剥离物质的恒星成分发出的光学光提供了这种质量的示踪剂，并且可以提供星团中暗物质的地图，这取决于它被剥离的时代。这个项目是为了观测几个星系团中弥漫的星系间光。所有这些星系团的质量估计都是通过维里定理从星系速度色散中推断出来的，通过流体静力平衡从x射线剖面中推断出来的，以及通过对背景星系引力透镜的观察得出的。漫射光的测量将为这些星团的质量分布提供额外的约束，并证实剥离假说。此外，星团内光的亮度强烈地限制了暗物质的矮星含量。由于在银河系的光晕中发现了由低质量天体引起的微透镜效应，因此出现了关于暗物质的低质量恒星含量的问题。先前对富星团Abell 2029核心的观测显示，在星团中心附近可能发生了潮汐剥离事件。如果这个解释是正确的，这将是一个极好的机会来研究星团演化中最重要的过程之一，它将通过对潮汐星云的高角度分辨率观测，以及对主要嵌入星系和附近星系的光谱观测进行更详细的研究。在超星系团的星系间区域探测到的漫射辐射不是来自恒星的光学光，而是来自热的电离气体的x射线辐射。一段时间以来，人们已经清楚，宇宙中重子物质的优势一定是以电离气体的形式存在的。如果超星系团中的气体处于临界温度，那么它应该发射轫致x射线。从本超星系团的平面上已经探测到10 keV的漫射能量，其性质将被研究。这种气体与CMB的相互作用也被认为是宇宙微波背景辐射（CMB）中Sunayev-Zel'dovich （SZ）效应的来源。预期的信号刚好在宇宙背景探测器（COBE）卫星的DMR辐射计的灵敏度极限，但应该可以被新的MAP和普朗克卫星天文台探测到。这种观测的可行性将通过模拟银河系污染对CMB辐射和CMB的随机波动来研究。还参与了一个利用RXTE x射线卫星探测附近沙普利超星团的x射线发射的项目，并将研究探测该星团中SZ效应的前景。

AbstractAST 99-70761BoughnModels of the formation of rich clusters of galaxies predict that from 10 % to 70 % of the initial mass of the galaxies has been tidally stripped away and now resides in the intracluster medium. The optical light from the stellar component of the stripped matter provides a tracer of this mass and could, depending on the epoch at which it was stripped, provide a map of the dark matter in the cluster. This project is to observe the diffuse, intergalactic light in several clusters of galaxies. All of these clusters have mass estimates deduced from galaxy velocity dispersions using the virial theorem, from X-ray profiles using hydrostatic equilibrium, and from observations of gravitational lensing of background galaxies. The measurement of diffuse light will provide an additional constraint on the distribution of mass in these clusters as well as confirmation of the stripping hypothesis. In addition, the brightness of intracluster light strongly constrains the dwarf star content of the dark matter. The question of the low mass star content of dark matter has arisen because of the discovery of microlensing by low mass objects in the halo of the Milky Way. The previous observations of the core of the rich cluster Abell 2029 have revealed what could be a tidal stripping event near the cluster center. If this interpretation is correct, there is an excellent opportunity to study one of the most important processes in the evolution of clusters and it will be studied in more detail with high angular resolution observations of the tidal nebula, as well as with spectroscopic observations of the primary embedded galaxy and the nearby galaxies.The diffuse emission to be detected in the intergalactic regions of superclusters of galaxies is not the optical light from stars but rather the X-ray emission from hot, ionized gas. It has been clear for some time that the preponderance of baryonic matter in the universe must be in the form of ionized gas. If this gas in superclusters is at the virial temperature then it should emit bremsstrahlung X-rays. Diffuse 10 keV energy emission from the plane of the local supercluster has been detected its nature will be investigated. The interaction of this gas with the CMB is also expected to be the source of a Sunayev-Zel'dovich (SZ) effect in the Cosmic Microwave Background (CMB) radiation. The expected signal is just at the sensitivity limit of the Cosmic Background Explorer (COBE) satellite's DMR radiometers, but should be detectable with the new MAP and PLANCK satellite observatories. The feasibility of such observations will be investigated by modeling both Galactic contamination to the CMB radiation and the random fluctuations in the CMB. There is also involvement in a project to detect X-ray emission from the nearby Shapley supercluster using the RXTE X-ray satellite and the prospects for detecting the SZ effect in that cluster will be investigated.