High Resolution Wide-Field Radio Imaging of the GOODS North Field

UoM administered thesis: Master of Science by Research

  • Authors:
  • Nicholas Wrigley

Abstract

The Great Observatories Origins Deep Survey North (GOODS-N) field has been surveyed across numerous bands revealing populations of both Starburst asnd Active Galactic Nuclei (AGN) radio galaxies over wide ranges of luminosities. It has been observed that the evolution in the starburst population appears to be different from that in the AGN population leading to a domination of starburst galaxies at low flux densities. The number of starbursts can only be disentangled from the entire population if each source can be individually classified, which usually requires high angular resolution imaging. This has motivated this study which expands the area of high resolution radio imaging in the GOODS-N field to increase the number of potentially classifiable sources. By use of wide-field imaging techniques, including polyhedral imaging, spectral deconvolution and subtraction, together with a semi-empirical primary beam-shape model for the combined MERLIN + VLA arrays, a 15 arc-minute diameter map is derived. This is the widest contiguous imaging yet obtained from combined MERLIN + VLA observations and represents an increase in area by over a factor of 2 - from approximately 72 square arc-minutes to over 175 square arc-minutes. A total of 87 additional high resolution imaged sources, above the 5sigma detection threshold, are presented and all lie outside the previously imaged 8.5' x 8.5' contiguous region but within 7.5' of the pointing centre. The majority of the objects are shown to exhibit extended structure, which is consistent with the view that the lower flux density sources are dominated by starburst emissions, rather than point-like AGN components. Several objects are examined in greater detail, with a view to classifying them, in order to determine the quality of the resulting map. This demonstrates that reliable imaging using the MERLIN + VLA array combination extends to approximately 7' from the pointing centre.

Details

Original languageEnglish
Awarding Institution
Supervisors/Advisors
  • Simon Garrington (Supervisor)
Award date3 Jan 2012