46 research outputs found
A sharp view on the low-frequency radio sky
The study of cosmic large-scale structure formation benefits from radio observations, because it provides an unbiased view on the early Universe. Distant radio galaxies and diffuse cluster sources generally have a steep spectrum, which implies an increased brightness towards lower frequencies (below 300 MHz). The quality of low-frequency radio observations is compromised by the propagation effects on cosmic radio waves passing through the ionosphere. In this thesis, we present a calibration method for low-frequency radio interferometric observations. This method significantly improves the quality of radio maps from archival observations as compared to other existing calibration methods. The method was used to produce one of the deepest high-resolution surveys at 153 MHz to date, including the detection of 16 candidate distant radio galaxies. Furthermore, the method was used in a study of the diffuse radio sources in the merging galaxy cluster Abell 2256. These observations support the theory of revival of old radio sources through cluster merger shock compression. Finally, we present a study of the cosmic large-scale structure near a radio galaxy in the early universe by using an optical selection technique for galaxies. The projected galaxy distribution appears to trace the cosmic structure during the assembly of galaxy clusters.UBL - phd migration 201
A Multi-resolution, Multi-epoch Low Radio Frequency Survey of the Kepler K2 Mission Campaign 1 Field
GalaxiesStars and planetary system
The angular power spectrum measurement of the Galactic synchrotron emission using the TGSS survey
Large scale structure and cosmolog
A low-frequency radio halo survey of the South Pole Telescope SZ-selected clusters with the GMRT
Large scale structure and cosmolog
Discovery of the correspondence between intra-cluster radio emission and a high pressure region detected through the Sunyaev-Zel'dovich effect
FR II radio galaxies at low frequencies:I. Morphology, magnetic field strength and energetics
Probing the non-thermal emission in the Perseus cluster with the JVLA
Large scale structure and cosmolog