Speaker
Description
Measuring the local primordial non-Gaussianity parameter, fNL, is crucial for understanding the nature of inflation, as it can rule out or confirm the various inflationary models. Although the current best constraint on fNL is achieved by the cosmic microwave background (CMB) bispectrum, datasets from large surveys (DESI, Euclid, LSST) are providing this decade another cosmic window to fundamental physics through the scale-dependent bias effect. The main challenge for performing fNL measurements from LSS are observational systematics, and a way to mitigate their impact is to perform cross-correlations with observables sensitive to different systematics like the CMB lensing. In this presentation, I will review the current status of the fNL measurements from LSS and discuss new methodologies for improving them. In particular, I will highlight the results from Bermejo-Climent et al. (2026), where we measure fNL with an uncertainty about ~14 from the Quaia quasar catalog by using a new observable called 'angular redshift fluctuations', in combination with quasar density and CMB lensing. This methodology improves by ~30% the previous analysis and is currently being applied to DESI and Euclid data.