Gamma-ray bursts, BL Lacs, Supernovae, and Interacting Galaxies

Abstract

Within the framework of star formation in starburst galaxies undergoing interactions, connections among the red quasars, the BL Lacs, and the Blazars with the gamma-ray bursts are discussed in the light of the "hypernovae" scenario. It is proposed that the gamma-ray bursts occur primarily in the star formation regions in starburst environments, and arise from the core-collapse of super-massive Wolf-Rayet stars, that are formed in interacting systems. In this interacting environment star formations cause supernovae explosions. As the stars explode, shock waves propagate outward and collide with the ambient medium, forming a high-density super-shell, where intense star formation begins; subsequently supernovae explosions within the shell cause an outward expansion of the shell. In another scenario of star formation the interactions among the large gas-rich low-surface brightness (LSB) spiral galaxies give rise to fragmentation of their tidal tails. These fragmented clouds collapse to compact dwarfs, which undergo rapid star formation. In such a scenario of interactions, where most quasars are observed, we discuss the MgII absorption lines in GRB 970508, whose spectra resemble a BL Lac object, and the spectral evolution of GRB 971214 that may also indicate a similar connection. Beside the BL Lac connection, the recent discovery of GRB 980425 in a nearby galaxy indicates asymmetric supernovae explosions that give rise to relativistic jets. We propose that the gamma-ray light curves arise due to inverse Compton scattering of soft-photons from precessing relativistic blobs of plasma moving in jets. This brings into light the mechanisms of supernova explosions, that give birth to relativistic jets.