Thesis

Polarisation of the Cosmic Microwave Background Radiation

• Call:

  IDPASC Portugal - PHD Programme 2015

• Academic Year:

  2015 / 2016

• Domains:

  Cosmology | Astrophysics

• Supervisor:

  Carla Sofia Carvalho

• Co-Supervisor:

  Antonio da Silva

• Institution:

  Faculdade de Ciências - Universidade de Lisboa

• Host Institution:

  Institute of Astrophysics and Space Sciences, FCUL

• Abstract:

  Cosmology is presently a very active field because of the large number of observations that are becoming available and that will allow us to characterize with great precision the nature and physical origin of the primordial cosmological perturbations, as well as of dark matter and dark energy. The cosmic microwave background (CMB) radiation provides a wealth of cosmological information that has led to major advances on our knowledge about the origin and evolution of the Universe. One of the ultimate challenges for CMB observations is to fully probe the CMB polarisation spectrum, from large to small angular scales, and to decipher the information encoded in the polarisation signal. This project is centred on cosmological data analysis and modelling in the context of the Planck and Euclid ESA satellite missions. It comprises two main objectives. The first objective consists in developing and implementing a novel estimator of the primary polarisation signal of the CMB. This signal can be measured from the gravitational lensing field to be extracted from CMB maps. This type of analysis will be particularly important in the sequence of the public release of CMB polarisation data by the Planck Collaboration and in the context of the tasks of the CMB Cross-Correlations Science Working Group of the Euclid Consortium. The second objective consists in assessing the robustness of the estimator of the primary CMB with respect to contamination by secondary CMB polarisation effects, which is not being considered in the current CMB data analysis. This requires the development of a detailed model of the secondary polarisation signals, such as the CMB quadrupole and double-scattering induced polarisations, which act as contaminants in the detection of the primary signal. This topic is related to the detection of CMB secondary polarisation by galaxy clusters with the ALMA interferometer. Another interesting topic of research that may be addressed within this project is the development of methods for the separation of the different polarisation components at the ALMA frequencies.