GRB progenitors at low metallicities

R. Hirschi$^1$, G. Meynet$^2$, A. Maeder$^2$

1- University of Basel, CH;
2- Geneva Observatory, CH

We calculated pre-supernova evolution models of single rotating massive stars. These models reproduce observations during the early stages of the evolution very well, in particular Wolf--Rayet (WR) populations and ratio between type II and type Ib,c supernovae at different metallicities (Z). Using these models we found the following results concerning long and soft gamma--ray burst (GRB) progenitors:

- GRBs coming from WO--type (SNIc) WR stars are only produced at low Z (LMC or lower).

- The upper metallicity limit for GRBs is reduced to Z ~ 0.004 (SMC) when the effects of magnetic fields are included.

- GRBs are predicted from the second (and probably the first) stellar generation onwards.

Reference: "Swift and GRBs: Unveiling the Relativistic Universe", San Servolo, Venice, 5-9 June 2006
Status: Conference proceedings


Comments: 5 pages