The gamma-ray burst/supernova connection, a distance estimator for gamma-ray bursts, and modeling gamma-ray burst afterglows

I present the strongest evidence to date for a connection between gamma-ray bursts (GRBs) and supernovae (SNe). In particular, I show that the unusual brightening and reddening of the optical afterglow of GRB 970228 about one month after the burst is naturally explained by a supernova. Furthermore, I present a possible, Cepheid-like luminosity estimator for the long bursts based on the variability of their light curves. The luminosity estimator can be used to measure luminosity distances to the long bursts that are accurate to a factor of ≈2. Also, the luminosity estimator suggests that GRB 980425 may well be associated with SN 1998bw at a redshift of z = 0.0085, and that GRB 980425 and the cosmological bursts may share a common physical origin. Additionally, I present a very general, Bayesian inference formalism for testing burst afterglow models and constraining the parameter values of acceptable models, and I present models for how extinction by dust, both in host galaxies and in our galaxy, and absorption by the Lyα forest and by H I in host galaxies, change the intrinsic spectrum of afterglows. Finally, I apply this Bayesian inference formalism and these extinction and absorption models to the measurements of the afterglow and host galaxy of GRB 971214.