Non-local dilaton coupling to dark matter: cosmic acceleration and pressure backreaction

L. Amendola, M. Gasperini and C. Ungarelli INAF/Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monteporzio Catone (Roma), Italy Dipartimento di Fisica, Università di Bari, Via G. Amendola 173, 70126 Bari, Italy INFN, Sezione di Bari, Bari, Italy CNR – Institute of Geosciences and Earth Resources, Via G. Moruzzi, 1, 56124 Pisa, Italy Abstract A model of non-local dilaton interactions, motivated by string duality symmetries, is applied to a scenario of “coupled quintessence” in which the dilaton dark energy is non-locally coupled to the dark-matter sources. It is shown that the non-local effects tend to generate a backreaction which – for strong enough coupling – can automatically compensate the acceleration due to the negative pressure of the dilaton potential, thus asymptotically restoring the standard (dust-dominated) decelerated regime. This result is illustrated by analytical computations and numerical examples.