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The C-Band All Sky Survey (C-BASS):Observing diffuse Galactic emission at 5 GHz.

Irfan, Melis Omer

[Thesis]. Manchester, UK: The University of Manchester; 2014.

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Abstract

ABSTRACT OF THESIS submitted by Melis Omer Irfan for the Degree of Doctor of Philosophy and entitled The C-Band All Sky Survey (C-BASS): Observing diffuse Galactic emission at 5 GHz. June 2014. University of Manchester.Measurements of the diffuse Galactic emission are used for both the interpretation of sensitive cosmic microwave background data and the understanding of our Galaxy. I examine the diffuse Galactic emission at a central frequency of 4.76 GHz using data from the C-Band All-Sky Survey (C-BASS). The technical work presented here fo- cuses on microphonic oscillation mitigation, receiver noise measurements and radio frequency interference detection. Northern C-BASS is a continuous comparison ra- diometer with a system temperature of 40 K, a knee frequency of 0.10 mHz in polari- sation and a noise level of 2 mK sqrt(s). A calibration scheme was devised, using astro- nomical calibrators, to convert the data to Kelvin and correct for atmospheric opacity. This scheme is stable to 1 % over several months and accurate to better than 5 %. A major systematic in the C-BASS data is ground emission. In this work the ground emission is modelled and subtracted from the data resulting. A first scientific anal- ysis of C-BASS Northern intensity data was made to investigate the contributions of free-free and synchrotron emission within the Galactic plane. The synchrotron spectral index was determined to be −2.63±0.07 between 0.408 and 4.76 GHz and −2.71±0.14 between 1.420 and 4.76 GHz and the ratio of free-free to synchrotron emission at 4.76 GHz was found to be 53± 8 % to 47± 8 %. Bringing in higher frequency data allowed for the detection of anomalous microwave emission associated with W43, W44 and W47 at a level of 4.9σ, 6.0σ and 3.4σ, respectively and demonstrated the need for C-BASS data to constrain the spectral form of AME within certain regions.

Bibliographic metadata

Type of resource:
Content type:
Administered thesis
Form of thesis:
Traditional
Type of submission:
Doctoral level ETD - final
Thesis title:
The C-Band All Sky Survey (C-BASS):Observing diffuse Galactic emission at 5 GHz.
Degree type:
Doctor of Philosophy
Degree programme:
PhD Astronomy & Astrophysics (42 month)
Publication date:
2014-06-18T19:00:33
Institution:
The University of Manchester
Location:
Manchester, UK
Total pages:
231
Abstract:
ABSTRACT OF THESIS submitted by Melis Omer Irfan for the Degree of Doctor of Philosophy and entitled The C-Band All Sky Survey (C-BASS): Observing diffuse Galactic emission at 5 GHz. June 2014. University of Manchester.Measurements of the diffuse Galactic emission are used for both the interpretation of sensitive cosmic microwave background data and the understanding of our Galaxy. I examine the diffuse Galactic emission at a central frequency of 4.76 GHz using data from the C-Band All-Sky Survey (C-BASS). The technical work presented here fo- cuses on microphonic oscillation mitigation, receiver noise measurements and radio frequency interference detection. Northern C-BASS is a continuous comparison ra- diometer with a system temperature of 40 K, a knee frequency of 0.10 mHz in polari- sation and a noise level of 2 mK sqrt(s). A calibration scheme was devised, using astro- nomical calibrators, to convert the data to Kelvin and correct for atmospheric opacity. This scheme is stable to 1 % over several months and accurate to better than 5 %. A major systematic in the C-BASS data is ground emission. In this work the ground emission is modelled and subtracted from the data resulting. A first scientific anal- ysis of C-BASS Northern intensity data was made to investigate the contributions of free-free and synchrotron emission within the Galactic plane. The synchrotron spectral index was determined to be −2.63±0.07 between 0.408 and 4.76 GHz and −2.71±0.14 between 1.420 and 4.76 GHz and the ratio of free-free to synchrotron emission at 4.76 GHz was found to be 53± 8 % to 47± 8 %. Bringing in higher frequency data allowed for the detection of anomalous microwave emission associated with W43, W44 and W47 at a level of 4.9σ, 6.0σ and 3.4σ, respectively and demonstrated the need for C-BASS data to constrain the spectral form of AME within certain regions.
Thesis main supervisor(s):
Thesis advisor(s):
Degree grantor:
Language:
en

Institutional metadata

University researcher(s):
Academic department(s):

Record metadata

Manchester eScholar ID:
uk-ac-man-scw:227354
Created by:
Irfan, Melis
Created:
18th June, 2014, 18:00:33
Last modified by:
Irfan, Melis
Last modified:
10th March, 2016, 22:17:43

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