Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.735940
Title: Measurements of diffuse galactic emission at 5 GHz with C-BASS
Author: Jew, Luke
ISNI:       0000 0004 6500 7668
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2017
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Abstract:
The C-Band All-Sky Survey (C-BASS) is a project to produce an all-sky map in intensity and polarization at a central frequency of 5 GHz with 1 GHz bandwidth and approximately 1 degree resolution. The central frequency is low enough for the map to be dominated by synchrotron and free-free emission but high enough so that Faraday rotation and depolarization are small across most of the sky. The C-BASS map will enable a more accurate removal of contaminating foregrounds from measurements of the cosmic microwave background, particularly in polarization where the B-mode signal from inflation is likely to be orders of magnitude weaker than the diffuse Galactic foreground emission. To produce an all-sky map from the ground requires two telescopes, one in the northern and one in the southern hemisphere. This thesis focuses on analysis of C-BASS North data. The noise properties of time-ordered data are characterised by fitting a noise model to periodograms. Using simulations, the errors introduced into the C-BASS maps by a destriping mapmaker are quantified and we reduce the signal error by masking the brightest pixels during baseline offset estimation. Jackknife tests are used to test the C-BASS data for systematics and to test the accuracy of the sensitivity maps. In total intensity, the spectral index of diffuse Galactic emission between 5 GHz and 408 MHz is measured using an extended T-T plot method and the results are compared to simulations. The spectral index of polarized diffuse Galactic emission between 5 GHz and 30 GHz is estimated in 55 arcminute pixels, modelling the polarized intensity as a Rician random variable.
Supervisor: Taylor, Angela Sponsor: STFC
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.735940  DOI: Not available
Keywords: Radio telescopes ; Cosmic background radiation ; Radio astronomy ; Astrophysics ; Synchrotron radiation ; Foregrounds ; Diffuse Galactic emission ; Mapmaking ; Noise properties ; CMB
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