SNR-calibrated Type Ia supernova models

Badenes

et al. 2020

ApJ

Self Cite

Chandra X-ray observations of Kepler's supernova remnant indicate the existence of a high speed Fe-rich ejecta structure in the southwestern region. We report strong K-shell emission from Fe-peak elements (Cr, Mn, Fe, Ni), as well as Ca, in this Fe-rich structure, implying that those elements could be produced in the inner area of the exploding white dwarf. We found Ca/Fe, Cr/Fe, Mn/Fe and Ni/Fe mass ratios of 1.0-4.1%, 1.0-4.6%, 1-11% and 2-30%, respectively. In order to constrain the burning regime that could produce this structure, we compared these observed mass ratios with those in 18 one-dimensional Type Ia nucleosynthesis models (including both near-M Ch and sub-M Ch explosion models). The observed mass ratios agree well with those around the middle layer of incomplete Si-burning in Type Ia nucleosynthesis models with a peak temperature of ∼(5.0-5.3)×10 9 K and a high metallicity, Z > 0.0225. Based on our results, we infer the necessity for some mechanism to produce protruding Fe-rich clumps dominated by incomplete Si-burning products during the explosion. We also discuss the future perspectives of X-ray observations of Fe-rich structures in other Type Ia supernova remnants.

Section: W49b and Nickelmentioning

confidence: 99%

A Nucleosynthetic Origin for the Southwestern Fe-rich Structure in Kepler’s Supernova Remnant

Sato

Badenes

et al. 2020

ApJ

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“…As references, I have selected two explosion models suitable for normal-luminosity SNIa, characterized by an ejected mass of 56 Ni about M( 56 Ni) ∼ 0.5 − 0.7 M . The first model, sub-M Ch , is a central detonation of a sub-Chandrasekhar WD of mass M WD = 1.06 M (model 1p06 Z9e-3 std in Bravo et al 2019). The second one, M Ch , is a delayed detonation of a massive WD with central density ρ c = 3 × 10 9 g cm −3 and a deflagration-to-detonation transition density ρ DDT = 2.4 × 10 7 g cm −3 (model ddt2p4 Z9e-3 std in Bravo et al 2019).…”

Section: Methodsmentioning

confidence: 99%

“…One example of this kind of tables of NSE properties is given in Seitenzahl et al (2009). Recently, Bravo et al (2019) reported that the final yields computed using their NSE table might disagree by order of magnitude for some isotopes with respect to those obtained computing the NSE state properties on the fly in the hydrodynamical calculation. The discrepancy did not affect significantly either the total energy release, that is the final kinetic energy, or the ejected mass of 56 Ni, and was attributed to the interpolation procedure applied to obtain the NSE properties out of the ρ, T , and Y e table nodes.…”

Section: Nuclear Statistical Equilibriummentioning

confidence: 99%

The accuracy of post-processed nucleosynthesis

Monthly Notices of the Royal Astronomical Society

2020

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The computational requirements posed by multi-dimensional simulations of type Ia supernovae make it difficult to incorporate complex nuclear networks to follow the release of nuclear energy along with the propagation of the flame. Instead, these codes usually model the flame and use simplified nuclear kinetics with the goal to determine a sufficiently accurate rate of nuclear energy generation and, afterwards, postprocess the thermodynamic trajectories with a large nuclear network to obtain more reliable nuclear yields. In this work, I study the performance of simplified nuclear networks with respect to the reproduction of the correct nuclear yields. The first point I address is the definition of a strategy to follow the properties of matter in nuclear statistical equilibrium (NSE). I propose that the best approach is to use published tables of NSE properties together with a careful interpolation routine. Second, I test several simplified nuclear networks for the accuracy of the nucleosynthesis obtained through post-processing, compared with the nucleosynthesis resulting directly from a one-dimensional supernova code equipped with a large nuclear network. Short networks (iso7 and 13α) are able to give an accurate yield of 56 Ni, after post-processing, but can fail by order of magnitude predicting the ejected mass of even mildly abundant species (> 10 −3 M ). A network of 21 species reproduces the nucleosynthesis of Chandrasekhar and sub-Chandrasekhar explosions with average errors better than 20% for the whole set of stable elements and isotopes followed in the model.

“…1-3 show the evolution of key quantities related to the branching of explosive oxygen burning into either the α-rich or the α-poor tracks. Specifically, the plots show the evolution of a mass shell reaching a peak temperature of 4 × 10 9 K in models 1p06_Z2p25e-4_ξ CO 0p9 and 1p06_Z2p25e-2_ξ CO 0p9, described in Bravo et al (2019). In short, both models simulate the detonation of a WD with mass 1.06 M made of carbon and oxygen, whose progenitor metallicities are respectively Z = 2.25 × 10 −4 (strongly sub-solar metallicity, hereafter the low-Z case) and Z = 0.0225 (about 1.6 times solar, hereafter the high-Z case).…”

Section: O(pα) 13 N and Metallicitymentioning

confidence: 99%

“…with f 0 = 0. The code used is the same as in Bravo et al (2019), where it is described in detail. The thermonuclear reaction rates used in the simulations are those recommended by the JINA REACLIB compilation (Cyburt et al 2010, hereafter REACLIB).…”

Section: O(pα) 13 N and Metallicitymentioning

confidence: 99%

¹⁶O(p,α)¹³N makes explosive oxygen burning sensitive to the metallicity of the progenitors of type Ia supernovae

2019

A&A

Even though the main nucleosynthetic products of type Ia supernovae belong to the iron-group, intermediate-mass alpha-nuclei (silicon, sulfur, argon, and calcium) stand out in their spectra up to several weeks past maximum brightness. Recent measurements of the abundances of calcium, argon, and sulfur in type Ia supernova remnants have been interpreted in terms of metallicity-dependent oxygen burning, in accordance with previous theoretical predictions. It is known that α-rich oxygen burning results from 16 O→ 12 C followed by efficient 12 C+ 12 C fusion reaction, as compared to oxygen consumption by 16 O fusion reactions, but the precise mechanism of dependence on the progenitor metallicity has remained unidentified so far. I show that the chain 16 O(p,α) 13 N(γ,p) 12 C boosts αrich oxygen burning when the proton abundance is large, increasing the synthesis of argon and calcium with respect to sulfur and silicon. For high-metallicity progenitors, the presence of free neutrons leads to a drop in the proton abundance and the above chain is not efficient. Although the rate of 16 O(p,α) 13 N can be found in astrophysical reaction rate libraries, its uncertainty is unconstrained.Assuming that all reaction rates other than 16 O(p,α) 13 N retain their standard values, an increase by a factor of approximately seven of the 16 O(p,α) 13 N rate at temperatures in the order 3 − 5 × 10 9 K is enough to explain the whole range of calcium-to-sulfur mass ratios measured in Milky Way and LMC supernova remnants. These same measurements provide a lower limit to the 16 O(p,α) 13 N rate in the mentioned temperature range, on the order of a factor of 0.5 with respect to the rate reported in widely used literature tabulations.