Can an Axion be the Dark Energy particle ?
  Following a phenomenological analysis done by the late Martin Perl for the
detection of the dark energy, we show that an axion of energy $1.5\times
10^{-3}~eV/c^2$ can be a viable candidate for the dark energy particle. In
particular, we obtain the characteristic length and frequency of the axion as a
quantum particle. Then, employing a relation that connects the energy density
with the frequency of a particle, i.e., $\rho\sim f^{4}$, we show that the
energy density of axions, with the aforesaid value of mass, as obtained from
our theoretical analysis is proportional to the dark energy density computed on
observational data, i.e., $\rho_{a}/\rho_{DE}\sim \mathcal{O}(1)$.
