Speaker
Description
Initial matter density perturbations during the primordial era are set in motion by inflation, dictating the subsequent formation and evolution of large-scale structure. In this research, we explored primordial non-Gaussianity (f_nl) in large-scale structures at z = 1.0 and z = 1.5, focusing on how improvements of the new and upcoming Euclid and SKA instruments will refine f_nl measurements, a critical test for inflationary theory and the standard model. Using an advanced bispectrum model, we analyzed systematic uncertainties from observational biases such as galaxy bias, redshift-space distortions, and gravitational lensing, applying statistical analysis based on two and three-point correlators. Probing the bispectrum up to k ≤ 10⁻⁴/Mpc, we incorporated second-order matter density perturbations to ensure theoretical predictions align with large-scale structure observations. SKA was shown to achieve tighter constraints on f_nl (5.65), outperforming Euclid (25.0). These improvements are attributed to distinct observational biases in SKA’s 21-cm hydrogen background compared to Euclid’s galaxy clustering measurements. Despite these advances, the simplest inflation models predict f_nl ≈ 1, a benchmark that remains difficult to reach even with upcoming instruments. This research confirmed key non-Gaussianity features, including bispectrum peaks at equality scales, a downward trend at larger k-scales, and BAO signatures at sub-horizon scales. It also emphasized SKA’s improved systematics in clarifying cosmic inflation. Finally, we established the need for higher-order correlators, GR effects, and cosmological gravitational waves to enhance observational precision and expand the range of observable scales. Steps toward these advancements will further refine f_nl constraints, improving our understanding of inflationary physics.
