Warm dark energy
  Motivated by some of the recent swampland conjectures, we study the
implementation for the late time acceleration of the Universe of a mechanism
developed by Anber and Sorbo in the context of primordial inflation, in which
an axion field can slowly roll in a steep potential due to additional friction
provided by its coupling to some U(1) gauge field. We first study the
realization of this mechanism in N = 2 supergravity models resulting from
string compactifications on Calabi--Yau manifolds. We then study the transition
between matter domination and the axion domination, and show that indeed the
backreaction of the produced gauge field can sufficiently slow the motion of
the axion, so to produce the present accelerated era. We finally study the
transition from a pre-inflationary matter or radiation domination to primordial
inflation. In the regime that we could explore numerically, the evolution is
characterized by stages of faster axion roll (and consequent bursts of gauge
field amplification) intermitted by stages of slower roll, with a pattern that
"oscillates'' about the steady state Anber and Sorbo solution, but that does
not appear to relax to it.
