First constraints on the running of non-Gaussianity

Area of Science:

• Cosmology
• Astrophysics
• Particle Physics

Background:

• Primordial non-Gaussianity deviates from the standard cosmological model's predictions.
• The "local" model is a popular framework for describing primordial non-Gaussianity.
• Scale-dependent non-Gaussianity offers a more generalized and potentially more realistic description.

Purpose of the Study:

• To constrain a scale-dependent generalization of the "local" model for primordial non-Gaussianity.
• To determine the running parameter n(fNL) using observational data.
• To assess the impact of priors on parameter constraints.

Main Methods:

• Utilizing temperature map data from the Wilkinson Microwave Anisotropy probe (WMAP).
• Implementing a scale-dependent model: f(NL)(k) = f*(NL) (k/k(piv))(n)(fNL).
• Marginalizing over the amplitude parameter f*(NL) to obtain constraints on n(fNL).

Main Results:

• Constrained the running parameter n(fNL) to be 0.30(-1.2)(+1.9) at 95% confidence.
• Demonstrated that constraints are sensitive to prior probability assignments.
• Established baseline limits for future, more precise measurements.

Conclusions:

• The study provides the first constraints on scale-dependent primordial non-Gaussianity within the "local" model framework.
• Future data from Planck and large-scale structure surveys are expected to significantly improve these constraints.
• These improved constraints will be crucial for testing and differentiating between various inflationary models.