Observing inflationary reheating

Area of Science:

• Cosmology
• Particle Physics
• Astrophysics

Background:

• Reheating is a critical epoch linking cosmic inflation with the hot Big Bang phase.
• The observational properties of reheating remain poorly understood despite its theoretical importance.
• Cosmic Microwave Background (CMB) anisotropies provide a window into the early universe.

Purpose of the Study:

• To investigate the constraints imposed by Planck satellite measurements on the kinematic properties of the reheating era.
• To analyze the impact of reheating on the Bayesian evidence of inflationary models.
• To assess the influence of reheating parameters on model selection in cosmology.

Main Methods:

• Derivation of marginalized posterior distributions for the reheating parameter across approximately 200 slow-roll inflation models.
• Statistical weighting of models based on their Bayesian evidence for explaining Planck 2013 CMB data.
• Analysis of how assumptions about reheating (e.g., equation of state) affect constraints.

Main Results:

• Planck 2013 CMB measurements reduce the posterior-to-prior volume for reheating parameters by an average of 40% across most inflationary models.
• The constraints on reheating properties can be enhanced or reduced based on specific assumptions or scenarios.
• Bayesian evidence for inflationary models is shown to be substantially influenced by reheating characteristics.

Conclusions:

• Current precision of CMB data necessitates the inclusion of reheating history information for accurate model performance evaluation.
• The study highlights the observational power of CMB data in probing the reheating epoch.
• Understanding reheating is crucial for a comprehensive picture of the early universe and inflationary cosmology.