Tracking solutions in tachyon cosmology

摘要: We perform a thorough phase-plane analysis of the flow defined by equations motion FRW Universe filled with tachyonic fluid plus barotropic one. The tachyon potential is assumed to be inverse square form, thus allowing for two-dimensional autonomous system equations. Friedmann constraint, combined convenient choice coordinates, renders physical state compact. find fixed-point solutions, and discuss whether or not they represent attractors. way two fluids contribute at late times fractional energy density depends on how fast redshifts. If it does enough, takes over times, but if opposite happens, situation will completely dominated fluid; instead there residual non-negligible contribution from subject restrictions coming nucleosynthesis.