Lagrangian description of cosmic fluids: Mapping dark energy into unified dark energy

• Type: Article in International Scientific Journal
• Date: 2020

Authors

Ferreira, VMC (Author) Other; Avelino, PP (Author) FCUP; Azevedo, RPL (Author) Other

Journal

Title: Physical Review D - Particles, Fields, Gravitation and Cosmology

Vol. 102

ISSN: 1550-7998

Publisher: American Physical Society

Indexing

ISI Web of Knowledge - 8 Citations

Scopus - 8 Citations

Other information

Authenticus ID: P-00S-T4P

DOI: 10.1103/physrevd.102.063525

Abstract (EN): We investigate the appropriateness of the use of different Lagrangians to describe various components of the cosmic energy budget, discussing the degeneracies between them in the absence of nonminimal couplings to gravity or other fields, and clarifying some misconceptions in the literature. We further demonstrate that these degeneracies are generally broken for nonminimal coupled fluids, in which case the identification of the appropriate on-shell Lagrangian may become essential in order to characterize the overall dynamics. We then show that models with the same on-shell Lagrangian may have different proper energy densities and use this result to map dark energy models into unified dark energy models in which dark matter and dark energy are described by the same perfect fluid. We determine the correspondence between their equation of state parameters and sound speeds, briefly discussing the linear sound speed problem of unified dark energy models as well as a possible way out associated with the nonlinear dynamics.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 14