Searching for Primordial Non-Gaussianity - Spectroscopic Surveys and Zero-Bias Tracers

Explore advanced techniques for detecting primordial non-Gaussianity in this 20-minute conference lecture from a cosmology workshop. Learn how spectroscopic 3D surveys can probe inflation signatures through local-type primordial non-Gaussianity, despite challenges from cosmic variance, bias uncertainty, and shot noise on large scales. Discover how zero-bias tracers—objects with effective linear bias approaching zero—can reduce sampling variance and make the scale-dependent signature from f_NL more detectable. Examine recent findings from the AbacusPNG simulation suite showing how incorporating secondary halo and galaxy properties like concentration, environment, and non-local bias can dramatically improve modeling of the inflation-specific bias parameter b_φ, reducing uncertainties in f_NL measurements by factors of 2-5. Follow the ongoing research applying these methods to DESI and SPHEREx mock catalogs to identify optimal zero-bias tracer populations that maintain sufficient number density and redshift accuracy. Understand the transformative potential of cosmic velocity measurements through the kinematic Sunyaev-Zel'dovich (kSZ) effect in the cosmic microwave background, and how combining density and velocity tracers could achieve unity precision in f_NL measurements—a breakthrough that could either challenge current cosmological paradigms or rule out entire classes of inflationary models.