Present and Early Universe with Tachyon and Phantom Field

Abstract

Recent astrophysical data obtained from high redshift surveys of Supernovae; COBE to WMAP predicts that the present universe is accelerating. It is also believed that the universe might have come through an inflationary phase in the past. Inflation is permitted with an equation of state p = \(\omega\)p , whare \(\omega\) = -1 such a state however, may be obtained either with a scalar field or an imperfect fluid in general relativity. Most successful theory developed so far is based on the dynamics of scalar field with a suitable potential which driven inflation and describe the evolution of the early universe. However, the present acceleration may be described with \(\omega\) < - 1 . Such an equation of state is not permitted with usual matters in the standard model of Particle physics. Thus a modification of the matter sector of the Einstein’s equation with new fields, perhaps a new physics, is to be explored. Such a condition is attained if one considers exotic fields. Such exotic fields are tachyon, phantom etc. Focusing on recent developments, I discuss inflation in the early universe and present accelerating phase of the universe considering tachyon and phantom field.