>Magister Scientiae - MSc / Next-generation surveys of the large-scale structure of the Universe will be of great
importance in allowing us to extract invaluable information about the nature of the
Universe and the physical laws that govern it, at a higher precision than previously possible.
In particular, they will allow us to more closely study primordial non-Gaussianity,
a feature which leaves an imprint on the power spectrum of galaxies on the ultra-large
scales and which acts as a powerful probe of the physics of the early Universe. To investigate
the extent to which upcoming surveys will be able to improve our knowledge
of primordial non-Gaussianity, we perform a forecast to predict the observational constraints
on local-type primordial non-Gaussianity, as well as an extension that includes
a scale dependence. We study the constraining power of a multi-tracer approach, where
information from different surveys is combined to help suppress cosmic variance and
break parameter degeneracies. More specifically, we consider the combination of a 21cm
intensity mapping survey with each of two different photometric galaxy surveys, and
also examine the effect of including CMB lensing as an additional probe. The forecast
constraint from a combination of SKA1, a Euclid-like (LSST-like) survey and a CMB
Stage 4 lensing experiment is (fNL) ' 0:9 (1:4) which displays a factor of 2 improvement
over the case without CMB lensing, indicating that the surveys considered are
indeed complementary. The constraints on the running index of the scale-dependent
model are forecast as (nNL) ' 0:12 (0:22) from the same combination of surveys.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uwc/oai:etd.uwc.ac.za:11394/7082 |
| Date | January 2019 |
| Creators | Matthewson, William |
| Contributors | Maartens, Roy, Ballardini, Mario |
| Publisher | University of the Western Cape |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Rights | University of the Western Cape |
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