RUI: Diffuse Emissions from Clusters and Superclusters of Galaxies

富星系团形成的AST99-70761 Boughn型模型预测，星系初始质量的10%到70%已经被潮汐剥离，现在位于星系团内介质中。来自被剥离物质的恒星成分的光学光提供了这一质量的示踪，并可能根据它被剥离的纪元，提供星系团中暗物质的地图。这个项目是为了观察几个星系团中漫射的星际光。所有这些星系团的质量估计都是从使用维里定理的星系速度色散、使用流体静力平衡的X射线剖面和背景星系的引力透镜观测得出的。漫反射光的测量将对这些星系团中的质量分布提供额外的约束，并证实剥离假说。此外，星系团内光的亮度强烈地制约着暗物质中的矮星含量。由于发现了银河系光晕中低质量天体的微透镜，暗物质的低质量恒星含量的问题出现了。之前对丰富星系团Abell 2029核心的观测揭示了星系团中心附近可能发生的潮汐剥离事件。如果这种解释是正确的，就有很好的机会来研究星系团演化中最重要的过程之一，并将通过对潮汐星云的高角度分辨率观测以及对原始嵌入星系和附近星系的光谱观测来更详细地研究这一过程。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射线发射。很明显，宇宙中重子物质的优势一定是以电离气体的形式存在。如果超星系团中的气体处于维里温度，那么它应该会发射出韧致X射线。局域超星系团平面的扩散10keV能量辐射已被探测到，其性质有待进一步研究。这种气体与CMB的相互作用也有望成为宇宙微波背景(CMB)辐射中Sunayev-Zel‘dovich(SZ)效应的来源。预计的信号只是在宇宙背景探测器(COBE)卫星的DMR辐射计的灵敏度极限，但应该可以用新的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对CMB辐射的污染和CMB中的随机波动来研究。还参与了一个利用RXTE X射线卫星探测附近Shapley超星系团的X射线辐射的项目，并将调查探测该星系团中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.