Central engine models Y NSNS merger model (Paczynski1986; Eichleret al 1989) Y Collapsar models Woosley 1993; Paczynski1998 MacFadyen Woosley 1999) Y Magnetar model(Usov 1992; Duncan& Thompson 1992) Y NSSS phase transition models( Cheng Dai 1996; Dai& Lu 1998a; Paczynski& Haensel 2005) Y Supranova models(Vietri& Stella 1998)Central engine models ✓ NS-NS merger model (Paczynski 1986; Eichler et al. 1989) ✓ Collapsar models (Woosley 1993; Paczynski 1998; MacFadyen & Woosley 1999) ✓ Magnetar model (Usov 1992; Duncan & Thompson 1992) ✓ NS-SS phase transition models (Cheng & Dai 1996; Dai & Lu 1998a; Paczynski & Haensel 2005) ✓ Supranova models (Vietri & Stella 1998)