Recent observational advances have enabled high resolution mapping of ${^{44}}$Ti in core-collapse supernova (CCSN) remnants. Comparisons between observations and models provide stringent constraints on the CCSN mechanism. However, past work has identified several uncertain nuclear reaction rates that influence ${^{44}}$Ti and ${^{56}}$Ni production in post-processing model calculations. We evolved one dimensional models of $15~M_{\odot}$, $18~M_{\odot}$, $22~M_{\odot}$ and $25~M_{\odot}$ stars from zero-age main sequence through CCSN using {\tt MESA} (Modules for Experiments in Stellar Astrophysics) and investigated the previously identified reaction rate sensitivities of ${^{44}}$Ti and ${^{56}}$Ni production. We tested the robustness of our results by making various assumptions about the CCSN explosion energy and mass-cut. We found a number of reactions that have a significant impact on the nucleosynthesis of ${^{44}}$Ti and ${^{56}}$Ni, particularly for lower progenitor masses. Notably, the reaction rates $^{13}{\rm N}(α,p)^{16}{\rm O}$, $^{17}{\rm F}(α,p)^{20}{\rm Ne}$, $^{52}{\rm Fe}(α,p)^{55}{\rm Co}$, $^{56}{\rm Ni}(α,p)^{59}{\rm Cu}$, $^{57}{\rm Ni}(n,p)^{57}{\rm Co}$, $^{56}{\rm Co}(p,n)^{56}{\rm Ni}$, $^{39}{\rm K}(p,γ)^{40}{\rm Ca}$, $^{47}{\rm V}(p,γ)^{48}{\rm Cr}$, $^{52}{\rm Mn}(p,γ)^{53}{\rm Fe}$, $^{57}{\rm Co}(p,γ)^{58}{\rm Ni}$, and $^{39}{\rm K}(p,α)^{36}{\rm Ar}$ are influential for a large number of model conditions. Furthermore, we found the list of influential reactions identified by previous post-processing studies of CCSN shock-driven nucleosynthesis is likely incomplete, motivating future larger-scale sensitivity studies.
We investigate core-collapse supernova (CCSN) nucleosynthesis with self-consistent, axisymmetric (2D) simulations performed using the radiation-hydrodynamics code Chimera. Computational costs have traditionally constrained the evolution of the nuclear composition within multidimensional CCSN models to, at best, a 14-species $α$-network capable of tracking only $(α,γ)$ reactions from $^{4}$He to $^{60}$Zn. Such a simplified network limits the ability to accurately evolve detailed composition and neutronization or calculate the nuclear energy generation rate. Lagrangian tracer particles are comm…
A protoneutron star produced in a core-collapse supernova (CCSN) drives a wind by its intense neutrino emission. We implement active-sterile neutrino oscillations in a steady-state model of this neutrino-driven wind to study their effects on the dynamics and nucleosynthesis of the wind in a self-consistent manner. Using vacuum mixing parameters indicated by some experiments for a sterile $ν_s$ of $\sim 1$ eV in mass, we observe interesting features of oscillations due to various feedback. For the higher $ν_s$ mass values, we find that oscillations can reduce the mass loss rate and the wind vel…
We investigate the impact of asymmetric neutrino-emissions on explosive nucleosynthesis in core-collapse supernovae (CCSNe) of progenitors with a mass range of 9.5 to 25$M_{\odot}$. We perform axisymmetric, hydrodynamic simulations of the CCSN explosion with a simplified neutrino-transport, in which anti-correlated dipolar emissions of $ν_{\rm e}$ and ${\bar ν}_{\rm e}$ are imposed. We then evaluate abundances and masses of the CCSN ejecta in a post-processing manner. We find that the asymmetric $ν$-emission leads to the abundant ejection of $p$- and $n$-rich matter in the high-$ν_{\rm e}$ and…
The details of the physical mechanism that drives core-collapse supernovae (CCSNe) remain uncertain. While there is an emerging consensus on the qualitative outcome of detailed CCSN mechanism simulations in 2D, only recently have high-fidelity 3D simulations become possible. Here we present the results of an extensive set of 3D CCSN simulations using high-fidelity multidimensional neutrino transport, high-resolution hydrodynamics, and approximate general relativistic gravity. We employ a state-of-the-art 20 solar mass progenitor generated using the Modules for Experiments in Stellar Astrophysi…
Production of radioactive $^{22}$Na in core-collapse supernovae: the Ne-E(L) component in presolar grains and its possible consequences on supernova observations
Neutrino-driven ejecta in core collapse supernovae (CCSNe) offer an interesting astrophysical scenario where lighter heavy elements between Sr and Ag can be synthesized. Previous studies emphasized the important role that ($α,n$) reactions play in the production of these elements, particularly in neutron-rich and alpha-rich environments. In this paper, we have investigated the sensitivity of elemental abundances to specific ($α,n$) reaction-rate uncertainties under different astrophysical conditions. Following a Monte Carlo nucleosynthesis study with over 36 representative astrophysical wind c…
Through numerical simulations, it is predicted that the gravitational waves (GWs) reflect the characteristics of the core-collapse supernova (CCSN) explosion mechanism. There are multiple GW excitation processes that occur inside a star before its explosion, and it is suggested that the GWs originating from the CCSN have a mode for each excitation process in terms of time-frequency representation. Therefore, we propose an application of the Hilbert-Huang Transform (HHT), which is a high-resolution time-frequency analysis method, to analyze these GW modes for theoretically probing and increasin…
The cosmic evolution of the neutron star merger (NSM) rate can be deduced from the observed cosmic star formation rate. This allows to estimate the rate expected in the horizon of the gravitational wave detectors advanced Virgo and ad LIGO and to compare those rates with independent predictions. In this context, the rapid neutron capture process, or r process, can be used as a constraint assuming NSM is the main astrophysical site for this nucleosynthetic process. We compute the early cosmic evolution of a typical r process element, Europium. Eu yields from NSM are taken from recent nucleosynt…
We present a linear stability analysis of the fast-pairwise neutrino flavor conversion based on a result of our latest axisymmetric core-collapse supernova (CCSN) simulation with full Boltzmann neutrino transport. In the CCSN simulation, coherent asymmetric neutrino emissions of electron-type neutrinos ($ν_{\rm e}$) and their anti-particles ($\barν_{\rm e}$), in which the asymmetry of $ν_{\rm e}$ and $\barν_{\rm e}$ is anti-correlated with each other, occur at almost the same time as the onset of aspherical shock expansion. We find that the asymmetric neutrino emissions play a crucial role on …
Radioactive isotopes produced in core-collapse supernovae (CCSNe) provide useful insights into the underlying processes driving the collapse mechanism and the origins of elemental abundances. Their study generates a confluence of major physics research, including experimental measurements of nuclear reaction rates, astrophysical modeling, and $γ$-ray observations. Here we identify the key nuclear reaction rates to the nucleosynthesis of observable radioactive isotopes in explosive silicon-burning during CCSNe. Using the nuclear reaction network calculator SkyNet and current REACLIB reaction ra…
In this fourth paper of the series, we use the parametrized, spherically symmetric explosion method PUSH to perform a systematic study of two sets of non-rotating stellar progenitor models. Our study includes pre-explosion models with metallicities Z=0 and Z=Z$_{\odot}\times 10^{-4}$ and covers a progenitor mass range from 11 up to 75 M$_\odot$. We present and discuss the explosion properties of all models and predict remnant (neutron star or black hole) mass distributions within this approach. We also perform systematic nucleosynthesis studies and predict detailed isotopic yields as function …
We analyzed the growth of non-spherical perturbations in supersonic accretion flows. We have in mind the application to the post-bounce phase of core-collapse supernovae (CCSNe). Such non-spherical perturbations have been suggested by a series of papers by Arnett, who has numerically investigated violent convections in the outer layers of pre-collapse stars. Moreover, Couch & Ott (2013) demonstrated in their numerical simulations that such perturbations may lead to a successful supernova even for a progenitor that fails to explode without the fluctuations. This study investigated the linear gr…
In this review, we first reassess the supernova remnant paradigm for the origin of galactic cosmic rays in the light of recent cosmic-ray data acquired by the Voyager 1 spacecraft. We then describe the theory of light element nucleosynthesis by nuclear interaction of cosmic rays with the interstellar medium and outline the problem of explaining the measured Be abundances in old halo stars of low metallicity with the standard model for the galactic cosmic ray origin. We then discuss the various cosmic ray models proposed in the literature to account for the measured evolution of the light eleme…
Recent studies have highlighted the sensitivity of core-collapse supernovae (CCSNe) models to electron-capture (EC) rates on neutron-rich nuclei near the N=50 closed-shell region. In this work, we perform a large suite of one-dimensional CCSN simulations for 200 stellar progenitors using recently updated EC rates in this region. For comparison, we repeat the simulations using two previous implementations of EC rates: a microphysical library with parameterized N=50 rates (LMP), and an older independent-particle approximation (IPA). We follow the simulations through shock revival up to several s…
The neutrino-driven wind from proto-neutron stars is a proposed site for r-process nucleosynthesis, although most previous work has found that a wind heated only by neutrinos cannot produce the third r-process peak. However, several groups have noted that introducing a secondary heating source within the wind can change the hydrodynamic conditions sufficiently for a strong r-process to proceed. One possible secondary heating source is gravito-acoustic waves, generated by convection inside the proto-neutron star. As these waves propagate into the wind, they can both accelerate the wind and shoc…
Physical Conditions for Synthesis of Sc, Ti, and V in Neutrino-driven Supernovae
Astronomical Science Program, Graduate Institute for Advanced Studies, SOKENDAI（日本国立天文台大学大学院高等研究院天文学专业）；National Astronomical Observatory of Japan, National Institutes of Natural Sciences（日本国立天文台，国立自然科学研究所）；Department of Physics, Faculty of Science and Engineering, Konan University（神户学院大学理工学部物理学科）；Yukawa Institute for Theoretical Physics, Kyoto University（京都大学汤川理论物理研究所）；Department of Astronomy, Graduate School of Science, The University of Tokyo（东京大学理学研究科天文学系）
In the context of core-collapse supernova explosions (CCSNe), the interaction of standing accretion shocks with upstream vorticity perturbations is investigated by linear theory analysis. The endothermic effect associated to the nuclear dissociation, which takes place right behind the shock wave, affects the amplitude of the perturbations amplified/generated across the front. For upstream disturbances whose characteristic size is much larger than the post-shock dissociation-layer thickness, the effect of nuclear dissociation can be reduced to that of considering the global endothermic effect t…
We investigate the relationship between explosion energy and nucleosynthesis in Population III supernovae and provide nucleosynthetic results for the explosions of stars with progenitor masses of $15\,\mathrm{M}_\odot$, $20\,\mathrm{M}_\odot$, $30\,\mathrm{M}_\odot$, $40\,\mathrm{M}_\odot$, $60\,\mathrm{M}_\odot$, and $80\,\mathrm{M}_\odot$, and explosion energies between approximately $10^{50}$ erg and $10^{53}$ erg. We find that the typical abundance pattern observed in metal-poor stars are best matched by supernovae with progenitor mass in the range $15\,\mathrm{M}_\odot$ - $30\,\mathrm{M}_…
We present a systematic numerical relativity study of the mass ejection and the associated electromagnetic transients and nucleosynthesis from binary neutron star (NS) mergers. We find that a few $10^{-3}\, M_\odot$ of material are ejected dynamically during the mergers. The amount and the properties of these outflow depend on binary parameters and on the NS equation of state (EOS). A small fraction of these ejecta, typically ${\sim}10^{-6}\, M_\odot$, is accelerated by shocks formed shortly after merger to velocities larger than $0.6\, {\rm c}$ and produces bright radio flares on timescales o…
