Diffuse radio emission in a galaxy cluster merger at frequency ranging from 150 MHz to 18 Ghz

Abstract

Galaxies, including our own Milky Way Galaxy, are vast assemblies of stars and gas. Clusters of galaxies consist of tens to hundreds of galaxies and are the largest gravitationally bound structures in the universe. They are ideal laboratories to study the formation and evolution of cosmic structure. Zwicky was the first to examine the Coma galaxy cluster in 1933, by using the virial theorem to infer the existence of unseen matter, which he referred to as Dunkle Materie 'dark matter’. Galaxy clusters have become an important cosmological tool in the last two decades for studying the accelerated expansion of the universe caused by dark energy. Recently, we have learned that these clusters show the peculiar characterstics i.e. they are not as simple as they appear. We now know that galaxy cluster mergers are the most energetic events in the universe and that these clusters frequently collided in the early universe. Most clusters are really the result of ‘cluster mergers’, which are collisions between galaxy clusters. These collisions have major impact on the structure and evolution of the clusters and the cosmological conclusions we draw from observing them. The goal of the research program proposed here is to observe a two of these cluster mergers at several different frequencies.According to 2dF galaxy redshift surveys (Peacock et al 2001), clusters of galaxies are formed in the large-scale filamentary structure of the Universe at the present epoch.A slice of the Millennium Simulation (Springel et al 2005) is shown in Fig. 1.1 (left). It is a visual impression of the distribution of the dark matter on large scales in the Universe at the present epoch. A cluster of galaxies formed at the intersection of the filaments is shown in Fig. 1.1 (right).