Quintessential Inflation in Palatini Gravity
  We study a model of quintessential inflation in the context of Palatini
gravity. As a representative example, we consider the Peebles-Vilenkin model of
quintessential inflation with a small non-minimal coupling to gravity, which is
consistent with the most recent Planck measurements. At the end of inflation,
the inflaton field passes through a tachyonic region and it leads to explosive
particle production through the tachyonic preheating process. After preheating,
the Universe becomes dominated by the kinetic energy of the inflaton and enters
a period of kination. Eventually, the total energy density of the Universe
becomes dominated by radiation, resulting in reheating. We find that the model
predicts the reheating temperature values $T_{\rm{RH}} \sim \mathcal{O}(10^3 -
10^8) \, \rm{GeV}$, which is significantly above the temperature of Big Bang
Nucleosynthesis. Following reheating, the inflaton field rolls down the
quintessence potential until it freezes. Since the quintessence remains frozen
until the present day, the residual potential energy density at this field
value explains the observed dark energy density.
