How much 56Ni can be produced in Core-Collapse Supernovae? : Evolution and Explosions of 30 - 100 Msun Stars

TL;DR

This study investigates the maximum amount of nickel-56 that can be produced in core-collapse supernovae from very massive stars, exploring how progenitor mass and explosion energy influence nucleosynthesis outcomes.

Contribution

It provides the first detailed modeling of nickel-56 synthesis in stars up to 100 solar masses, linking progenitor properties to supernova brightness.

Findings

Nickel-56 production increases with progenitor mass and explosion energy.

Producing 4 solar masses of nickel-56 is feasible for certain massive stars with high explosion energies.

Achieving 13 solar masses of nickel-56 requires very large explosion energies or more massive cores.

Abstract

Motivated by the discovery of extremely bright supernovae SNe1999as and 2006gy, we have investigated how much 56Ni mass can be synthesized in core-collapse massive supernovae (SNe). We calculate the evolution of several very massive stars with initial masses M <~ 100 Msun from the main-sequence to the beginning of the Fe-core collapse and simulate their explosions and nucleosynthesis. In order to avoid complications associated with strong mass-loss, we only consider metal-poor stars with initial metallicity Z = Zsun/200. However, our results are applicable to higher metallicity models with similar C+O core masses. The C+O core mass for the 100Msun model is M_CO = 42.6Msun and this is the heaviest model in the literature for which Fe-core collapse SN is explored. The synthesized 56Ni mass increases with the increasing explosion energy and progenitor mass. For the explosion energy of E_51 = E/10^{51} erg =30, for example, the 56Ni masses of M(56Ni) = 2.2, 2.3, 5.0, and 6.6 Msun can be produced for the progenitors with initial masses of 30, 50, 80 and 100 Msun (or C+O core masses M_CO = 11.4, 19.3, 34.0 and 42.6 Msun), respectively. We find that producing M(56Ni) ~ 4Msun as seen in SN1999as is possible for M_CO >~ 34 Msun and E_{51} >~ 20. Producing M(56Ni) ~ 13Msun as suggested for SN2006gy requires a too large explosion energy for M_CO <~ 43Msun, but it may be possible with a reasonable explosion energy if M_CO >~ 60Msun.