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Register a new userNucleosynthesis in multi-dimensional SNIa explosions
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C. Travaglio
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We present the results of nucleosynthesis calculations based on multidimensional (2D and 3D) hydrodynamical simulations of the thermonuclear burning phase in SNIa. The detailed nucleosynthetic yields of our explosion models are calculated by post-processing the ejecta, using passively advected tracer particles. The nuclear reaction network employed in computing the explosive nucleosynthesis contains 383 nuclear species. We analyzed two different choices of ignition conditions (centrally ignited, in which the spherical initial flame geometry is perturbated with toroidal rings, and bubbles, in which multi-point ignition conditions are simulated). We show that unburned C and O varies typically from ~40% to ~50% of the total ejected material.The main differences between all our models and standard 1D computations are, besides the higher mass fraction of unburned C and O, the C/O ratio (in our case is typically a factor of 2.5 higher than in 1D computations), and somewhat lower abundances of certain intermediate mass nuclei such as S, Cl, Ar, K, and Ca, and of 56Ni. Because explosive C and O burning may produce the iron-group elements and their isotopes in rather different proportions one can get different 56Ni-fractions (and thus supernova luminosities) without changing the kinetic energy of the explosion. Finally, we show that we need the high resolution multi-point ignition (bubbles) model to burn most of the material in the center (demonstrating that high resolution coupled with a large number of ignition spots is crucial to get rid of unburned material in a pure deflagration SNIa model).
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We investigate the metallicity effect (measured by the original 22Ne content) on the detailed nucleosynthetic yields for 3D hydrodynamical simulations of the thermonuclear burning phase in SNe Ia. Calculations are based on post-processes of the ejecta, using passively advected tracer particles, as explained in details by Travaglio et al.(2004). The nuclear reaction network employed in computing the explosive nucleosynthesis contains 383 nuclear species. For this work we use the high resolution multi-point ignition (bubbles) model b30_3d_768 (Travaglio et al.2004 for the solar metallicity case), and we cover a metallicity range between 0.1xZ_sun up to 3xZ_sun. We find a linear dependence of the 56Ni mass ejected on the progenitors metallicity, with a variation in the 56Ni mass of ~25% in the metallicity range explored. Moreover, the largest variation in 56Ni occurs at metallicity greater than solar. Almost no variations are shown in the unburned material 12C and 16O. The largest metallicity effect is seen in the alpha-elements. Finally, implications for the observed scatter in the peak luminosities of SNe Ia are also discussed.
We investigate explosive nuclear burning in core collapse supernovae by coupling a tracer particle method to one and two-dimensional Eulerian hydrodynamic calculations. Adopting the most recent experimental and theoretical nuclear data, we compute the nucleosynthetic yields for 15 Msun stars with solar metallicity, by post-processing the temperature and density history of advected tracer particles. We compare our results to 1D calculations published in the literature.
Core-collapse supernovae (CCSNe) are the extremely energetic deaths of massive stars. They play a vital role in the synthesis and dissemination of many heavy elements in the universe. In the past, CCSN nucleosynthesis calculations have relied on artificial explosion methods that do not adequately capture the physics of the innermost layers of the star. The PUSH method, calibrated against SN1987A, utilizes the energy of heavy-flavor neutrinos emitted by the proto-neutron star (PNS) to trigger parametrized explosions. This makes it possible to follow the consistent evolution of the PNS and to ensure a more accurate treatment of the electron fraction of the ejecta. Here, we present the Iron group nucleosynthesis results for core-collapse supernovae, exploded with PUSH, for two different progenitor series. Comparisons of the calculated yields to observational metal-poor star data are also presented. Nucleosynthesis yields will be calculated for all elements and over a wide range of progenitor masses. These yields can be immensely useful for models of galactic chemical evolution.
In a previously presented proof-of-principle study, we established a parametrized spherically symmetric explosion method (PUSH) that can reproduce many features of core-collapse supernovae for a wide range of pre-explosion models. The method is based on the neutrino-driven mechanism and follows collapse, bounce and explosion. There are two crucial aspects of our model for nucleosynthesis predictions. First, the mass cut and explosion energy emerge simultaneously from the simulation (determining, for each stellar model, the amount of Fe-group ejecta). Second, the interactions between neutrinos and matter are included consistently (setting the electron fraction of the innermost ejecta). In the present paper, we use the successful explosion models from Ebinger et al. (2018) which include two sets of pre-explosion models at solar metallicity, with combined masses between 10.8 and 120 M$_{odot}$. We perform systematic nucleosynthesis studies and predict detailed isotopic yields. The resulting $^{56}$Ni ejecta are in overall agreement with observationally derived values from normal core-collapse supernovae. The Fe-group yields are also in agreement with derived abundances for metal-poor star HD84937. We also present a comparison of our results with observational trends in alpha element to iron ratios.
We explore SNIa as p-process sources in the framework of two-dimensional SNIa models using enhanced s-seed distributions as directly obtained from a sequence of thermal pulse instabilities. The SNIa WD precursor is assumed to have reached the Chandrasekhar mass limit in a binary system by mass accretion from a giant/main sequence companion. We apply the tracer-particle method to reconstruct the nucleosynthesis from the thermal histories of Lagrangian particles, passively advected in the hydrodynamic calculations. For each particle we follow the explosive nucleosynthesis with a detailed nuclear reaction network. We select tracers within the typical temperature range for p-process production, 1.5-3.7 109K, and analyse in detail their behaviour, exploring the influence of different s-process distributions on the p-process nucleosynthesis. We find that SNIa contribute to a large fraction of p-nuclei, both the light p-nuclei and the heavy-p nuclei at a quite flat average production factor. For the first time, the very abundant Ru and Mo p-isotopes are reproduced at the same level as the heavy p-nuclei. We investigate the metallicity effect on the p-process production. Starting with a range of s-seeds distributions obtained for different metallicities, running SNIa two-dimensional models and using a simple chemical evolution code, we give estimates of the SNIa contribution to the solar p-process composition. We find that SNIa contribute for at least 50% at the solar p-nuclei composition, in a primary way.
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