Coupled and catalyzed quintessence: A general approach.

摘要

A cosmological theory that predicts a late-time accelerated attractor on which there is a constant ratio of dark matter to dark energy can be said to solve the Coincidence Problem. Such theories can naturally arise from conformal transformations of non-standard gravity which generate couplings between scalar fields and matter. The present work determines the class of these theories that can solve the Coincidence Problem. Within the class that can do so, a new model dubbed Catalyzed Quintessence is found that shares many features with the Coupled Quintessence Model but which solves the Coincidence Problem in a larger region of parameter space. The perturbation equations were derived in both Catalyzed Quintessence and generalized Coupled Quintessence Models so that predictions of these models could be compared to Cosmic Microwave Background (CMB) and Large-Scale Structure (LSS) data. The Coupled Quintessence Model is implemented in CAMB, a public code for calculating predicted CMB and LSS power spectra, and order-of-magnitude estimates for its free parameters were found using a Markov Chain Monte Carlo algorithm.