COSMOLOGIES WITH PHOTON CREATION AND THE 3K RELIC RADIATION SPECTRUM

A new Planckian type distribution for cosmologies with photon creation is derived using thermodynamics and semiclassical considerations. Thi s spectrum is preserved during the evolution of the universe and compa tible with the present spectral shape of the cosmic microwave backgrou nd radiation (CMBR). Accordingly, the widely spread feeling that cosmo logies with continuous photon creation are definitely ruled out by the COBE limits on deviation of the CMBR spectrum from blackbody shape sh ould be reconsidered. It is argued that a crucial test for this kind o f cosmologies is provided by measurements of the CMBR temperature at h igh redshifts. For a given redshift z greater than zero, the temperatu re is smaller than the one predicted by the standard FRW model.