The cosmological constant has attained a leading role in recent researches in cosmology. We extend the cosmic no-hair theorem to non-minimally coupled theories of gravity where ordinary matter is also present in the form of a perfect fluid. To achieve this goal we give a set of conditions for obtaining de Sitter expansion independently of any initial data (no fine-tuning problem), that is, we introduce a time-dependent (effective) cosmological constant. Finally, we apply the results to some specific models.
A possible way to define an effective cosmological constant in scalar-tensor cosmologies
CAPOZZIELLO, SALVATORE;DE RITIS, RUGGIERO;RUBANO, CLAUDIO;SCUDELLARO, PAOLO
2000
Abstract
The cosmological constant has attained a leading role in recent researches in cosmology. We extend the cosmic no-hair theorem to non-minimally coupled theories of gravity where ordinary matter is also present in the form of a perfect fluid. To achieve this goal we give a set of conditions for obtaining de Sitter expansion independently of any initial data (no fine-tuning problem), that is, we introduce a time-dependent (effective) cosmological constant. Finally, we apply the results to some specific models.File in questo prodotto:
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