Observational constraints on the interacting dark energy - dark matter
  (IDM) model
  Particle creation (or annihilation) mechanisms, described by either quantum
field theoretical models, or by the thermodynamics of irreversible processes,
play an important role in the evolution of the early Universe, like, for
example, in the warm inflationary scenario. Following a similar approach, based
on the thermodynamics of open systems, in the present work we investigate the
consequences of the interaction, decay, and particle generation in a
many-component Universe, containing dark energy, dark matter, radiation, and
ordinary matter, respectively. In this model, due to the interaction between
these components, and of the corresponding thermodynamical properties, the
conservation equations of different cosmological constituents are not satisfied
individually. We introduce a thermodynamic description of the Universe, in
which two novel physical aspects, the particle number balance equations, and
the creation pressures, are considered, thus making the cosmological evolution
equations thermodynamically consistent. To constrain the free parameters of the
model several observational data sets are employed, including the Planck data
sets, Riess 2020, BAO, as well as Pantheon data. By using a scaling ansatz for
the dark matter to dark energy ratio, and by imposing constraints from
Planck+Riess 2020 data, this model predicts an acceptable value for the Hubble
parameter, and thus it may provide a solution to the so-called Hubble tension
problem, much debated recently.
