Dynamics of tachyon dark energy on large scales and its imprint on the observed galaxy power spectrum

Abstract

In the present work, we study the large scale matter power spectrum as well as the observed galaxy power spectrum for a noncanonical 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 the concordance $\mathrm{\ensuremath{\Lambda}}$ cold dark matter ($\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$) model are studied for different relevant quantities. Our study shows that the noncanonical tachyon dark energy model produces enhanced gravitational potentials and comoving density contrast, as well as linear growth factor for matter perturbations compared to $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$. It is also observed that, for tachyon dark energy models, there is suppression of power on large scales compared to both the $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ model as well as previously studied canonical scalar field models.