Is it possible to observationally distinguish adiabatic quartessence from [lambda]CDM ?

• Verfasst von: Amendola, Luca [VerfasserIn]
• Titel: Is it possible to observationally distinguish adiabatic quartessence from [lambda]CDM ?
• Verf.angabe: L. Amendola, M. Makler, R.R.R. Reis, and I. Waga
• Fussnoten: Im Titel ist das Lambda als griechischer Buchstabe dargestellt ; Gesehen am 15.11.2017
• Titel Quelle: Enthalten in: Physical review / D
• Jahr Quelle: 2006
• Band/Heft Quelle: 74(2006,6) Artikel-Nummer 063524, 5 Seiten
• ISSN Quelle: 1550-2368
• ISSN Quelle: 1089-4918
• DOI: doi:10.1103/PhysRevD.74.063524
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1565371909

Abstract

The equation of state (EOS) in quartessence models interpolates between two stages: p≃0 at high energy densities and p≈−ρ at small ones. In the quartessence models analyzed up to now, the EOS is convex, implying increasing adiabatic sound speed (c2s) as the energy density decreases in an expanding universe. A nonnegligible c2s at recent times is the source of the matter power spectrum problem that plagued all convex (nonsilent) quartessence models. Viability for these cosmologies is only possible in the limit of almost perfect mimicry to ΛCDM. In this work we investigate if similarity to ΛCDM is also required in the class of quartessence models whose EOS changes concavity as the Universe evolves. We focus our analysis in the simple case in which the EOS has a steplike shape, such that at very early times p≃0, and at late times p≃const<0. For this class of models a nonnegligible c2s is a transient phenomenon and could be relevant only at a more early epoch. We show that agreement with a large set of cosmological data requires that the transition between these two asymptotic states would have occurred at high redshift (zt≳38). This leads us to conjecture that the cosmic expansion history of any successful nonsilent quartessence is (practically) identical to the ΛCDM one.