Observational constraints on particle production during inflation

Resonant particle production, along with many other physical processes which change the effective equation of state (EOS) during inflation, introduces a feature in the primordial power spectrum which in many models has a step-like shape. We calculate observational constraints on resonant particle production, parametrized in the form of an effective step height, Neff and location in k-space, kbreak. Combining data from the cosmic microwave background and the 2dF Galaxy Redshift Survey yields strong constraints in some regions of parameter space, although the range in k-space which can be probed is restricted to k~0.001−0.1h Mpc−1. We also discuss the implications of our findings for general models which change the effective EOS during inflation.