Published online by Cambridge University Press: 22 July 2013
The results of investigation of 43 peaked R-band light curves of optical transients ofgamma-ray bursts with known redshifts are presented. The parameters of optical transientswere calculated in the comoving frame, and then a search for pair correlations betweenthem was conducted. As a result of the statistical analysis, a strong correlation betweenthe peak luminosity and redshift was found for pure afterglows and the events withresidual gamma activity, which can’t be explained as an effect of observational selection.It suggests the cosmological evolution of the parameters of the local interstellar mediumaround the sources of gamma-ray burst. In the models of forward and reverse shock waves, arelation between the density of interstellar medium and redshift was built for gamma-rayburst afterglows. It was shown that for GRB host galaxies the star formation rateincreases with redshift.