"Constraining primordial non Gaussianity from the large-scale structure of the universe." par Annalisa Pillepich (Zurich)

Thursday 27 Nov 2008, 11:00 → 12:00 Europe/Paris

salle 9 (LPSC)

According to the standard scenario, the large-scale structure of the Universe that we recognize today under the form of groups and clusters of galaxies, filaments, and sheets is the result of gravitational instability of small density fluctuations generated at very early times. The statistical properties of these seeds are still unclear. The simplest inflationary models produce Gaussian fluctuations but other plausible scenarios give rise to mildly non-Gaussian density perturbations. For the first time, the upcoming generation of cosmic microwave background studies and galaxy redshift surveys should be able to detect signatures of primordial non-Gaussianity. In this talk, I will discuss how the abundance and clustering of galaxy groups and clusters from these surveys can be used to detect primordial non-Gaussianity. I will also show that another method has the potential to provide tighter constraints. A new generation of radio interferometers such as LOFAR, SKA, and MWA is currently being planned to detect 21cm radiation from the early universe. The observational issues are challenging, nonetheless such an effort is mainly motivated to study reionization and the dark ages. I will show that the three-point statistics of the brightness temperature can test the presence of primordial non-Gaussianity with unprecedented accuracy.