Massless scalar field in a de Sitter universe and its thermal flux

The time dependent wave equation for a conformally coupled massless scalar field in a de Sitter universe is examined. It is pointed out that the exact solutions of the radial equation valid over the 'whole range' can be found - unlike the corresponding situation on the Schwarzschild space-time. The power spectrum of Hawking radiation is evaluated after calculating the absorption probability at the horizon. The solution is seen to be well behaved at the origin. (author)