Thesis

Non-linear evolution of cosmic structure in the Euclid Universe beyond LCDM

• Call:

  IDPASC Portugal - PHD Programme 2019

• Academic Year:

  2019 / 2020

• Domains:

  Cosmology | Astrophysics

• Supervisor:

  Antonio da Silva

• Co-Supervisor:

  Nelson Nunes

• Institution:

  Faculdade de Ciências - Universidade de Lisboa

• Host Institution:

  Faculdade de Ciências - Universidade de Lisboa

• Abstract:

  CMB observations by the Planck satellite, combined with galaxy survey and supernovae data, show that a simple inflationary LCDM model with only six parameters provides a consistent description of the main global properties of the Universe on large scales. However, this baseline model has only moderate success on smaller scales, where tensions arise when CMB data is combined with other large-scale structure (LSS) datasets. Excursions beyond the Planck baseline model assuming extra parameters that describe alternative dark energy / modified gravity hypothesis or additional dark matter physics, have been used to try to reconcile observations, but different LSS probes (mostly sensitive to the linear evolution of cosmic structure) often favor different model excursions. The non-linear evolution of cosmic structure provides a unique way to further test the viability of these alternative conjectures. Numerical N-body simulation methods have already allowed to explore some classes of alternative models, but they have been conducted in an isolated way, using inconsistent baseline cosmology parameters, and more importantly, lack dedicated products that mimic existing or planned galaxy surveys. This type of systematic study is currently missing in most large-scale structure surveys and is clearly necessary for the upcoming ESA/Euclid satellite mission, which will measure the shapes of billions of galaxies and accurate redshifts of tens of millions of galaxies for weak gravitational lensing and galaxy clustering studies. The objective of this project is to perform a consistent study of the nonlinear growth of cosmological structure for alternative cosmological models and to develop a suite of Euclid simulation products that can be used to study degeneracies and identify ways to discriminate between alternative models using non-linear probes of large-scale structure.