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Title: The Sunyaev-Zel'dovich effect in galaxy clusters as a tool for estimating cosmological parameters
Author: Valkonen, Laura Elina
ISNI:       0000 0001 3541 9678
Awarding Body: University of Sussex
Current Institution: University of Sussex
Date of Award: 2007
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Clusters of galaxies provide us with a sensitive probe with which to study the Universe. Their mass function is strongly dependent on the cosmological parameters, which govern the dynamical evolution of the Universe and they also provide a representative sample of ~he Universal matter distribution. The Sunyaev-Zel'dovich effect (SZE) is a promising method for detecting clusters out to their form.ation redshift and has also been shown to be a good estimator for cluster masses, A combination. of X-ray and SZE data can also be used to measure the dista:nce to the cluster, independently of the cosmic distance ladder, allowing a measurement of the Hubble Constant. However, the success of SZE methods is highly dependent on a detailed understanding of the physics of galaxy clusters. We have undertaken a multi-wavelength survey of 8 ga:laxy clusters, the Viper Sunyaev-Zel'dovich Survey (VSZS), in order to assess and highlight the issues which may be encountered by upcoming large scale SZE surveys. Such surveys will not be able to study individual clus- . ters in great detail and will be reliant on the ·accuracy of scaling relations and assumed cluster models. \Ve have therefore imaged each cluster in our sample simultar;eously at three frequencies (150GHz, 220GHz and 280GHz) with the Arcminute Cosmology Bolometer Array Receiver (ACBAR), and have followed-up with X-ray observations (Chandra and XMM-Newton) and some optical observations (Gemini), in order to carry out a detailed analysis of the cluster ICM structure. We have made some of the highest significance detections of the SZE to date. Several clusters were detected at two frequencies, as a temperature increment at 280 GHz and a decrement at 150 GHz and some of these clusters were also resolved by the observations. Most of the VSZS sample were detected as SZE signals for the first time. Although Abell 3667 and lE0657-56 had been detected previously, these were now detected at two frequencies for the first time. We have added the results of the four fully analyzed VSZS clusters to the Y- T relation of Bonamente et al. (2007) and have found our points to lie well within the scatter of the relation, except fOr cluster A3112, which has possible radio source contamination. We have also found that cluster temperatures estimated from the Y - T relation are better overall at tracing the X-ray spectral temperature than the Lx - T derived temperatures.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available