Stellar Yields of Rotating First Stars. II. Pair-instability Supernovae and Comparison with Observations

Abstract

Recent theory predicts that a first star is born with a massive initial mass of 100 M . Pair instability supernova (PISN) is a common fate for such a massive star. Our final goal is to prove the existence of PISN and thus the high mass nature of the initial mass function in the early universe by conducting abundance profiling, in which properties of a hypothetical first star is constrained by metal-poor star abundances. In order to determine reliable and useful abundances, we investigate the PISN nucleosynthesis taking both rotating and non-rotating progenitors for the first time. We show that the initial and CO core mass ranges for PISNe depend on the envelope structures: non-magnetic rotating models developing inflated envelopes have a lower-shifted CO mass range of ∼ 70-125 M , while non-rotating and magnetic rotating models with deflated envelopes have a range of ∼ 80-135 M . However, we find no significant difference in explosive yields from rotating and non-rotating progenitors, except for large nitrogen production in nonmagnetic rotating models. Furthermore, we conduct the first systematic comparison between theoretical yields and a large sample of metal-poor star abundances. We find that the predicted low [Na/Mg] ∼ −1.5 and high [Ca/Mg] ∼ 0.5-1.3 abundance ratios are the most important to discriminate PISN signatures from normal metal-poor star abundances, and confirm that no currently observed metal-poor star matches with the PISN abundance. Extensive discussion on the non-detection is finally made.

Fitting formulae for evolution tracks of massive stars under extreme metal-poor environments for population synthesis calculations and star cluster simulations

“…We follow the time evolutions of stars with M = 8, 10,13,16,20,25,32,40,50,65,80,100,125, and 160 M for log(Z/Z ) = -2, -4, -5, -6 and −8 from the zero age main-sequence (ZAMS) to the carbon ignitions at the stellar centers. We use a 1D stellar evolution code, HOSHI code (Takahashi et al 2016(Takahashi et al , 2018(Takahashi et al , 2019Yoshida et al 2019). Here we describe some details for the chemical mixing by convection and input physics in the stellar evolution model.…”

“…We include thermonuclear reactions and weak interactions (β decays and electron captures) concerning to the nuclear species, so the evolution calculation from hydrogen burning (pp-chain and CNO cycles) until core-collapse (Si burning and photo-disintegration) is available. The rates of thermonuclear reactions are adopted from JINA REACLIB v1 (Cyburt et al 2010) except for 12 C(α, γ) 16 C. The rate of 12 C(α, γ) 16 O is adopted from Caughlan & Fowler (1988) and is multiplied by a factor of 1.2 (Takahashi et al 2018).…”

Black Hole Formation and Explosion from Rapidly Rotating Very Massive Stars

“…If additional angular momentum transport mechanisms work efficiently during the stellar evolution phase, the final core angular velocity would be reduced. For example, Takahashi et al (2018) performed 1D stellar evolution calculations of rotating VMSs with and without the effect of the magnetic stress modeled by the Tayler-Spruit dynamo (TS dynamo, Spruit (2002)). They indi-cated that the magnetic models have 10 times slower rotation rate than the non-magnetic models.…”

The COMBS survey – I. Chemical origins of metal-poor stars in the Galactic bulge

“…Given the first stars have a top-heavy IMF (Tumlinson 2006;Bromm 2013), the stars enriched from the first stars would have higher levels of α-enhancement than the thick disk or halo. The theoretical yields of α elements from a non-rotating PISNe are on the order of [α/Fe] ∼ 2 dex (Takahashi et al 2018) while the lowest metallicity stars in the local disk have [α/Fe] ∼ 0.4 dex.…”