2008ApJ...685.1063B

The present scenario for high-luminosity long gamma-ray bursts is strongly influenced by the paper of Fruchter and coworkers. Whereas the main contention of this paper that these GRBs occur in low-metallicity irregular galaxies is based on a considerable collection of observational results and although the main thesis is doubtless correct, the paper does not explain the dynamics that produces such GRBs and much of the discussion not directly concerning the main thesis is incorrect. We propose a dynamics and elucidate how the Fruchter et al. results may be tested, in our neighborhood in the LMC, suggesting that LMC X-3 is a relic of a high-luminosity explosion, probably accompanied by a GRB and hypernova explosion. The way to test our suggestion is to measure the system velocity of the present black hole. We correct errors of the Fruchter et al. paper in stellar evolution, so that the study of GRBs is consistent with it. We show that the subluminous GRB 060218 had a low-mass black hole as central engine.