AstrophysicalSfactor of theC12(α,γ)O16

Abstract

Determination of the accurate astrophysical S factor of 12 C(α, γ) 16 O reaction has been regarded as a holy grail of nuclear astrophysics for decades. In current stellar models, a knowledge of that value to better than 10% is desirable. Due to the practical issues, tremendous experimental and theoretical efforts over nearly 50 years are not able to reach this goal, and the published values contradicted with each other strongly and their uncertainties are 2 times larger than the required precision. To this end we have developed a Reduced R-matrix Theory, based on the classical Rmatrix theory of Lane and Thomas, which treats primary transitions to ground state and four bound states as the independent reaction channels in the channel spin representation. With the coordination of covariance statistics and error propagation theory, a global fitting for almost all available experimental data of 16 O system has been multi-iteratively analyzed by our powerful code. A reliable, accurate and self-consistent astrophysical S factor of 12 C(α, γ) 16 O was obtained with a recommended value Stot (300) = 162.7 ± 7.3 keV b (4.5%) which could meet the required precision.

Constraints from Gravitational-wave Detections of Binary Black Hole Mergers on the 12C(α, γ)16O Rate

“…Thus improving our understanding of this key rate is of critical importance to stellar astrophysics. The difficulty in measuring the rate occurs due to the negligible cross section of the reaction at temperatures relevant for helium burning in stars (An et al 2015(An et al , 2016. Thus nuclear experiments can only provide data for much higher energies (i.e., temperatures), from which we extrapolate down to astrophysically relevant energies.…”

Constraints from gravitational wave detections of binary black hole mergers on the $^{12}\rm{C}\left(α,γ\right)^{16}\!\rm{O}$ rate

“…It plays a key role in governing the evolution and composition of stars beyond the main sequence, from the C/O ratio in white dwarfs (Salaris et al 1997;Straniero et al 2003;Fields et al 2016), whether a star will form a neutron star or a black hole (Brown et al 2001;Woosley et al 2002;Tur et al 2007;West et al 2013;Sukhbold & Adams 2020), and the amount of 12 C r.j.farmer@uva.nl and 16 O in the Universe (Boothroyd & Sackmann 1988;Thielemann et al 1996) Thus improving our understanding of this key rate is of critical importance to stellar astrophysics. The difficulty in measuring the rate occurs due to the negligible cross section of the reaction at temperatures relevant for helium burning in stars (An et al 2015(An et al , 2016. Thus nuclear experiments can only provide data for much higher energies (i.e.…”

The impact of the uncertainties in the 12C(α,γ)16O reaction rate on the evolution of low- to intermediate-mass stars

“…We consider the adopted rate from An et al (2016) (An_A) and the highest and lowest reaction rate within the uncertainties (An_H and An_L, respectively). However, the S-factor calculation of An et al (2015), seems to neglect external contributions for ground state energy levels, making this approximation not valid for high precision analysis (Deboer et al 2017). Therefore, we treat the uncertainties of the 12 C(𝛼, 𝛾) 16 O reaction rate from An et al ( 2016) as arbitrary differences to determine the effect of the urgent need for more precise 12 C(𝛼, 𝛾) 16 O reaction rate uncertainties, as claimed by Kunz et al (2002); Tur et al (2010).…”