In this paper we consider two models. First, we study tachyon-Gauss-Bonnet gravity and obtain the condition of the equation of state crossing $-1$. Second, we discuss the modified Gauss-Bonnet gravity with the tachyon field and show the condition of $\omega$ crossing $-1$. Also, we plot figures for $\omega$ numerically in special potential and coupling function.

• Received 16 March 2009

DOI:https://doi.org/10.1103/PhysRevD.79.123003