  We study the possibility of explaining the late time acceleration with an
axion field which is coupled with the dark matter sector of the energy budget
of the Universe. The axion field arises from the Ramond-Ramond sector of the
Type-IIB string theory. We study the background evolution of the Universe as
well as the growth of the matter perturbation in the linear regime. We
subsequently use the observational data from Sn-Ia, BAO measurements,
measurements of the Hubble parameter as well as the observational data for the
growth of the matter perturbation to constrain our model. Our results show that
coupled axion models are allowed to have larger deviation from cosmological
constant by the present observational data.
