In this thesis we push the boundaries of high-resolution imaging at radio frequencies between 100 and 200 MHz. Using the International LOFAR Telescope that spans across Europe we achieve sub... Show moreIn this thesis we push the boundaries of high-resolution imaging at radio frequencies between 100 and 200 MHz. Using the International LOFAR Telescope that spans across Europe we achieve sub-arcsecond angular resolution. We demonstrate mapping of the full field of view of the telescope at its native resolution and use the resulting images to study active galactic nuclei in the Lockman Hole field. Show less
It has now been well established that shocks and turbulent motions in the intra-cluster medium (ICM) generated through cluster mergers can produce large-scale synchrotron emission. However, the... Show moreIt has now been well established that shocks and turbulent motions in the intra-cluster medium (ICM) generated through cluster mergers can produce large-scale synchrotron emission. However, the underlying particle acceleration mechanisms responsible for the origin of these faint diffuse radio sources are not well understood. With the advent of new generation low-frequency radio telescopes and better calibration techniques it has now become possible to unveil low-frequency radio sky with unprecedented depth and sensitivity, that is full of potential for new discoveries. The first part of this dissertation presents the study to better understand the nature of revived fossil (radio) plasma sources in galaxy cluster and establish them as a distinct class of radio sources. The complexity of objects, observed with these new instruments are just tip of the iceberg of the population, and will challenge the traditional taxonomy of diffuse radio sources. The last part of the dissertation focuses on deriving the deepest radio source-counts at 150 MHz. This is one of the several cosmological tests to check feasibility of new cosmological models and a sanity check for the data reduction. The derived source-counts are also compared with the other existing determinations, as well as with state-of-the-art evolutionary models. Show less
