Pair creation supernovae at low and high redshift

摘要: Aims. Pair creation supernovae (PCSN) are thought to be produced from very massive low metallicity stars. The spectacularly bright SN 2006gy does show several signatures expected PCSNe. Here, we investigate the threshold below which PCSN can form and estimate their occurrence rate. Methods. We perform stellar evolution calculations for stars of 150 Mand 250 Mof (Z� / 5a ndZ� /20), analyze mass loss rates. Results. find that bifurcation between quasi-chemically homogeneous fast rotation conventional evolu- tion slower rotation, has been found earlier stars, persists in range considered here. Consequently, there two separate progenitor types: (I) rotators produce PCSNe Wolf-Rayet (II) generate hydrogen-rich yellow hypergiants. Conclusions. could occur at metallicities as high Z� /3, - assuming standard IMFs still valid birth rates results a rate about one per 1000 local universe, 100 redshift z = 5. WC-type restricted much lower metallicity.