Structure formation and CMBR anisotropy spectrum in the inflessence model

¹ Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235, USA
² Dipartimento di Fisica “E.R. Caianiello”, Università di Salerno and INFN, Sezione di Napoli, Gruppo Collegato di Salerno, via S. Allende, 84081 Baronissi (Salerno), Italy e-mail: winny@na.infn.it
³ Dipartimento di Scienze Fisiche, Università di Napoli and INFN, Sezione di Napoli, Compl. Univ. di Monte S. Angelo, Edificio G, via Cinthia, 80121 Napoli, Italy

Received: 17 March 2006
Accepted: 23 June 2006

Abstract

The inflessence model has recently been proposed in an attempt to explain both early inflation and present day accelerated expansion within a single mechanism. The model has been successfully tested against the Hubble diagram of Type Ia Supernovae, the shift parameter, and the acoustic peak parameter. As a further mandatory test, we investigate here structure formation in the inflessence model determining the evolution of matter density contrast in the linear regime. We compare the growth factor and the growth index to these same quantities for the successful concordance ΛCDM model with a particular emphasis on the role of the inflessence parameters . We also evaluate the anisotropy spectrum of the cosmic microwave background radiation (CMBR) to check whether the inflessence model may be in agreement with the observations. We find that, for large values of , structure formation proceeds in a similar way to that in the ΛCDM scenario, and it is also possible to nicely fit the CMBR spectrum.