2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/13850I argue that cosmic Gamma-ray Bursts (GRB) may be produced by collapses or mergers of stars made of `mirror' matter. The mirror neutrinos (which are sterile for our matter) produced at these events can oscillate into ordinary neutrinos. The annihilations or decays of the latter create an electron-positron plasma and subsequent relativistic fireball with a very low baryon load needed for GRBs. The concept of mirror matter is able to explain several key problems of modern astrophysics: neutrino anomalies, the missing mass, MACHO microlensing events and GRBs. Thus this concept becomes very appealing and should be considered quite seriously and attentively.7 pages, no figures.Presented at XXVII ITEP Winter School, Snegiri, Feb. 16 -- 24, 1999AstrophysicsHigh Energy Physics - Phenomenologytext