From nuclear multifragmentation reactions to supernova explosions

An approach toward the successful supernova explosion by physics of unstable nuclei

We study the explosion mechanism of collapse-driven supernovae by numerical simulations with a new nuclear EOS based on unstable nuclei. We report new results of simulations of general relativistic hydrodynamics together with the Boltzmann neutrino-transport in spherical symmetry. We adopt the new data set of relativistic EOS and the conventional set of EOS (Lattimer-Swesty EOS) to examine the influence on dynamics of core-collapse, bounce and shock propagation. We follow the behavior of stalled shock more than 500 ms after the bounce and compare the evolutions of supernova core.

Statistical approach for supernova matter

We formulate a statistical model for description of nuclear composition and equation of state of stellar matter at subnuclear densities and temperature up to 20 MeV, which are expected during the collapse and explosion of massive stars. The model includes nuclear, electromagnetic and weak interactions between all kinds of particles, under condition of statistical equilibrium. We emphasize importance of realistic description of the nuclear composition for understanding stellar dynamics and nucleosynthesis. It is demonstrated that the experience accumulated in studies of nuclear multifragmentati…

The Core-Collapse Supernova Explosion Mechanism

The explosion mechanism of core-collapse supernovae is a long-standing problem in stellar astrophysics. We briefly outline the main contenders for a solution and review recent efforts to model core-collapse supernova explosions by means of multi-dimensional simulations. We discuss several suggestions for solving the problem of missing or delayed neutrino-driven explosions in three-dimensional supernova models, including -- among others -- variations in the microphysics and large seed perturbations in convective burning shells. Focusing on the neutrino-driven mechanism, we summarise currents ef…

The Role of Nucleon Strangeness in Supernova Explosions

Recent hydrodynamical simulations of supernova (SN) evolution have highlighted the importance of a thorough control over microscopic physics responsible for such internal processes as neutrino heating. In particular, it has been suggested that modifications to the neutrino-nucleon elastic cross section can potentially play a crucial role in producing successful supernova explosions. One possible source of such corrections can be found in a nonzero value for the nucleon's strange helicity content $Δs$. In the present analysis, however, we show that theoretical and experimental progress over the…

Equilibrium constants of nuclear reactions in supernova explosions

We study the change in internal rotational energy in the transformation of protons to neutrons in the \b{eta}-decay reactions that take place in the collapse of the iron core of massive stars that precede type II supernova explosions. We consider an ensemble of electrons, protons, neutrons and neutrinos undergoing \b{eta}-decay reactions, treat the protons and neutrons as triatomic rotors, evaluate the equilibrium constant to obtain the change in rotational energy during the proton-to-neutron transformation. We estimate such change for a variety of conditions, and compare to the energy release…

强子-夸克相变引发的原致密星坍缩及其对超新星爆发的启示

Phase-transition-induced collapse of proto-compact stars and its implication for supernova explosions

本研究通过广义相对论流体动力学模拟，系统探索了强子-夸克相变诱导原致密星坍缩的结局，揭示了爆发成败对相变及夸克物质特性的依赖，并绘制了相图以指导未来观测与自洽研究。

Explosion Mechanisms of Core-Collapse Supernovae

Supernova theory, numerical and analytic, has made remarkable progress in the past decade. This progress was made possible by more sophisticated simulation tools, especially for neutrino transport, improved microphysics, and deeper insights into the role of hydrodynamic instabilities. Violent, large-scale nonradial mass motions are generic in supernova cores. The neutrino-heating mechanism, aided by nonradial flows, drives explosions, albeit low-energy ones, of ONeMg-core and some Fe-core progenitors. The characteristics of the neutrino emission from new-born neutron stars were revised, new fe…

Probing thermonuclear supernova explosions with neutrinos

Aims: We present neutrino light curves and energy spectra for two representative type Ia supernova explosion models: a pure deflagration and a delayed detonation. Methods: We calculate the neutrino flux from $β$ processes using nuclear statistical equilibrium abundances convoluted with approximate neutrino spectra of the individual nuclei and the thermal neutrino spectrum (pair+plasma). Results: Although the two considered thermonuclear supernova explosion scenarios are expected to produce almost identical electromagnetic output, their neutrino signatures appear vastly different, which allow a…