The effects of variations in nuclear interactions on nucleosynthesis in thermonuclear supernovae

Abstract

Context. Type Ia supernova explosions are violent stellar events important for their contribution to the cosmic abundance of iron peak elements and for their role as cosmological distance indicators. Aims. The impact of nuclear physics uncertainties on nucleosynthesis in thermonuclear supernovae has not been fully explored using comprehensive and systematic studies with multiple models. To better constrain predictions of yields from these phenomena, we investigate thermonuclear reaction rates and weak interaction rates that significantly affect yields in our underlying models. Methods. We have performed a sensitivity study by postprocessing thermodynamic histories from two different hydrodynamic, Chandrasekhar-mass explosion models. We have individually varied all input reaction and, for the first time, weak interaction rates by a factor of ten (up and down) and compared the yields in each case to yields using standard rates. Results. Of the 2305 nuclear reactions in our network, we find that in either model the rates of only 53 reactions affect the yield of any species with an abundance of at least 10 −8 M by at least a factor of two. 36 Cl rates significantly affect the yields of species in a model. Additional tests reveal that reaction rate changes over temperatures T > 1.5 GK have the greatest impact and that ratios of radionuclides that may be used as explosion diagnostics change by a factor of < ∼ 2 from the variation of individual rates by a factor of ten. Conclusions. Nucleosynthesis in the two adopted models is relatively robust to variations in individual nuclear reaction and weak interaction rates. Laboratory measurements of a limited number of reactions would, however, help to further constrain model predictions. In addition, we confirm the need for a detailed, consistent treatment of all relevant stellar weak interaction rates since simultaneous variation of these rates (as opposed to individual variation) has a significant effect on yields in our models.

Origin of the p -process radionuclides 92 Nb and 146 Sm in the early solar system and inferences on the birth of the Sun

“…This is derived from the 53 Cr abundance given by ref. 24, but we note that different models produce very similar 53 Mn/ 55 Mn ratios (42 Mn ratio in SNIa would result from a 10-fold increase of the 32 S(β + ) 32 P decay (43), in which case T isolation would decrease to ' 9 My. This possibility needs to be further investigated.…”

Solar abundance of manganese: a case for near Chandrasekhar-mass Type Ia supernova progenitors

“…At lower density, the 55 Co present in NSE is readily destroyed during the alpha-rich freeze-out via 55 Co(p, γ) 56 Ni (see Jordan et al 2003), resulting in a much lower final [Mn/Fe]. We note that a recent study has shown that the 55 Co to 56 Ni production ratio is rather insensitive to nuclear reaction rate uncertainties (Parikh et al 2013). …”

LATE-TIME PHOTOMETRY OF TYPE IA SUPERNOVA SN 2012cg REVEALS THE RADIOACTIVE DECAY OF 57Co

“…Model yields where the primary WD is significantly less massive than M Ch predict even lower 57 Ni/ 56 Ni ratios: the merger model of a 1.1M e CO WD with a 0.9M e CO WD of Pakmor et al (2012) predicts ∼1.1 times Solar and the pure detonation models of CO and ONe WDs of Marquardt et al (2015) predict around 0.3-0.5 times Solar. Parikh et al (2013) have found that the 57 Ni/ 56 Ni production ratio is very robust (at the 10% level) to individual changes of nuclear reaction rates by a factor of 10; rate uncertainties are therefore unlikely to solely account for the difference. Therefore, the high 57 Co/ 56 Co ratio we find appears to point toward a near-M Ch progenitor.…”