Nucleosynthesis in jets from Collapsars Shin-ichiro Fujimoto (KNCT, Japan), Collaboration with Nobuya Nishimura, & Masa-aki Hashimoto (Kyusyu Univ., Japan) OMEG07@Sapporo, Japan 2007.12.04

Collapsar model of gamma-ray bursts Collapsar = Rapidly rotating massive star collapsing to BH (Woosley 1993) During gravitational collapse of a massive star ( > about 20Msun) The central core collapses to a black hole (BH) Outer layers form an accretion disk around BH due to high angular momentum. Jets from an inner part of the disk. The jets are accelerated to relativistic velocities. We can observe a GRB if we locate on directions to jet propagation. Scenario plausible for GRB because of the discovery of GRB with a core collapse supernova (SN) (GRB980425/SN1998bw, GRB030329/SN2003dh)

Motivations R (rapid neutron capture)-process in collapsar jets Neutron-rich disk in a collapsar from 1D study Collapsar = New r-process site ? Variety of masses of 56Ni in SN with nearby GRBs GRB with hypernova (HN): GRB030329: M(56Ni) > 0.3 Msun GRB with normal SN: GRB060219: M(56Ni) < 0.1 Msun GRB without SN: GRB060505: M(56Ni) < 0.01 Msun  Can such the diversity be explained in light of collapsar model ? Based on 2D MHD simulations of collapsars with various distributions of rotation and B fields  Nucleosynthesis in jets from the collapsars R-process & masses of 56Ni No parameters other than initial conditions of a collapsar before core collapse

Numerical setup in MHD simulations 40Msun collapsar before the core collapse (Hashimoto 1995) Rapid, Moderate, or Slow core Vertical and uniform magnetic fields Angular velocity: R (rapid), M (moderate), S (slow) Magnetic field B0: 108G, 1010G, 1012G 9 collapsars: R8, R10, R12, no ejection of jets M8, M10, M12, ejection of jets S8, S10, S12 rapid moderate slow

Lagrangian evolution of the jets Distribution of jet particles: M12 3000km x 3000km Tracer particle method ρ,T↑ t=0.20s Lagrangian evolution from Eulerian evolution (M12). 2,000 tracer particles are initially placed from Fe core to O-rich layers. We can follow time evolution of position of all tracer particles. One can select particles (jet particles) that are ejected through the jets. 214 jet particles ρ,T↓ t=0.25s ρ,T↓ t=0.31s the onset of collapse: t = 0 s

Maximum densities and temperatures of jet particles Higher density & T states High density jet particles are expected to be neutron-rich due to p+e n 1e+11 1e+9g/cc 56Ni produced Similar to Type II SNe Incomplete Si burning Complete Si burning 1e+06 3e+9 3e+10 1e+9 g/cc B0=1010G Incomplete Si burning Complete Si Burning 3e+9 3e+10 B0=1012G

Ye vs maximum density of jet particles Ye = electron fraction (=electron par baryon) at T = 9e+9 K Ye = 0.4 more n-rich for Ye↓ 1e+9g/cc 1e+06 1e+11 B0=1010G Ye = 0.4 Many n-rich particles for M10, M12, & R12 1e+9g/cc R-process is expected to operate 1e+06 1e+11 B0=1012G

Composition of collapsar jets and Eu-scaled solar r-elements □: Eu-scaled solar r-nuclei Abundance profiles of collapsar jets are similar to those of the solar r-elements for A > 80-100 U,Th M12 R12 U,Th U,Th A=80 A=80

Ejected masses of 56Ni & r-elements Bright SNe (HNe) Enegetic jet with r-elements 0.12 & 0.3 Msun/s Normal SNe Weak or no SNe M(56Ni)ej↑ for Eej↑ Bright-ness of SNe Eej [1051 ergs]

Summary R-process in the jets Masses of 56Ni in the jets We have investigated nucleosynthesis inside the jets from collapsars, based on 2D MHD simulations of the collapsars in light of the collapsar model of GRBs R-process in the jets R-process in the energetic jets (Eej > 1051ergs) from three collapsars (M10, M12, R12) Even for a collapsar (M10) with moderate rotation (2.5Hz) and 1010G Large amounts of r-nuclei (> 0.01Msun) Masses of 56Ni in the jets Jets with Eej ↑, Mass of 56Ni ↑ The diversity of Ni56 mass in GRBs is likely to be explained in light of the collapsar model ApJ644, 1040, 2006 (MHD), ApJ656, 382, 2007 (r-proc.)