Revisiting Barrow's graduated inflationary universe: A warm perspective

It is presumed that thermal fluctuations present during inflationary epoch can make inflaton scalar field to interact with other fields resulting in the existence of a thermal component during the inflationary period. The presence of this thermal component assists structure formation and reduces reheating dependence as in the contemporary inflationary paradigm. This is known as warm inflation. In 1990 J.D. Barrow [26] considered a scenario of inflation with matter field having a phenomenological equation of state of the type p+ρ=γρλ,γ≠0 and λ constant. He called such inflationary scenarios as “graduated inflation”. In this work we reconsider the above equation of state in a scenario of warm inflation. Our aim would be to investigate and understand whether such matter can also act as a viable candidate for warm inflation.