  In the present work, we study the large scale matter power spectrum as well
as the observed galaxy power spectrum for non-canonical tachyon field dark
energy model considering the full general relativistic perturbation equations.
We form a set of coupled autonomous equations including both the background and
linearly perturbed quantities and obtain their solutions numerically with
proper set of initial conditions. We consider different scalar field potentials
for our study. Deviations from concordance $\Lambda$CDM model are studied for
different relevant quantities. Our study shows that non-canonical tachyon dark
energy model produces enhanced gravitational potentials, comoving density
contrast as well as linear growth factor for matter perturbations compared to
$\Lambda$CDM. It is also observed that for tachyon dark energy models, there is
suppression of power on large scales compared to both $\Lambda$CDM model as
well as previously studied canonical scalar field models.

Cosmology and Nongalactic Astrophysics