A sharp view on the low-frequency radio sky

Leiden Repository

A sharp view on the low-frequency radio sky

Type: Doctoral Thesis
Title: A sharp view on the low-frequency radio sky
Author: Intema, Hubertus Theodorus
Publisher: Leiden Observatory, Faculty of Science, Leiden University
Issue Date: 2009-08-26
Keywords: Calibration
Galaxy clusters
Ionosphere
Large-scale structure
Radio galaxies
Radio interferometry
Abstract: 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.
Description: Promotores: H.J.A. Röttgering, G.K. Miley
With summary in Dutch
Faculty: Faculteit der Wiskunde en Natuurwetenschappen
Citation: Intema, H., 2009, Doctoral thesis, Leiden University
Handle: http://hdl.handle.net/1887/13943
 

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