Abstract
If dark energy is dynamical due to the evolution of a scalar field, then in
general it is expected that the scalar is coupled to matter. While couplings to
the standard model particles are highly constrained by local experiments,
bounds on couplings to dark matter (DM) are only obtained from cosmological
observations and they are consequently weaker. It has recently be pointed out
that the coupling itself can become non-zero only at the time of dark energy
domination, due to the evolution of dark energy itself, leading to a violation
of the equivalence principle (EP) in the dark sector at late times. In this
paper we study a specific model and show that such late-time violations of the
EP in the DM sector are not strongly constrained by the evolution of the
cosmological background and by observables in the linear regime (e.g. from the
cosmic microwave background radiation). A study of perturbations in non-linear
regime is necessary to constrain late--time violations of the equivalence
principle much more strongly.
Users
Please
log in to take part in the discussion (add own reviews or comments).