Author:
Beltrán Jiménez Jose,Bettoni Dario,Figueruelo David,Teppa Pannia Florencia A.,Tsujikawa Shinji
Abstract
Abstract
We consider a cosmological scenario where the dark sector is
described by two perfect fluids that interact through a
velocity-dependent coupling. This coupling gives rise to an
interaction in the dark sector driven by the relative velocity of
the components, thus making the background evolution oblivious to
the interaction and only the perturbed Euler equations are affected
at first order. We obtain the equations governing this system with
the Schutz-Sorkin Lagrangian formulation for perfect fluids and
derive the corresponding stability conditions to avoid ghosts and
Laplacian instabilities. As a particular example, we study a model
where dark energy behaves as a radiation fluid at high redshift
while it effectively becomes a cosmological constant in the late
Universe. Within this scenario, we show that the interaction of
both dark components leads to a suppression of the dark matter
clustering at late times. We also argue the possibility that this
suppression of clustering together with the additional dark
radiation at early times can simultaneously alleviate the σ8
and H0 tensions.
Subject
Astronomy and Astrophysics
Cited by
15 articles.
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