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; A. A., Marino; Rubano, Claudio; Scudellaro, Paolo. - STAMPA. - Recent Developments in General Relativity:(2000), pp. 63-70. (Intervento presentato al convegno Recent Developments in General Relativity tenutosi a Cala Corvino-Monopoli (Bari) nel Sept. 21-25, 1998).
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
