scholarly journals Acoustic wave generation in collapsing massive stars with convective shells

2020 ◽  
Vol 493 (3) ◽  
pp. 3496-3512 ◽  
Author(s):  
Ernazar Abdikamalov ◽  
Thierry Foglizzo
Keyword(s):  
Acoustic Waves ◽  
Massive Stars ◽  
Core Collapse ◽  
Core Collapse Supernova ◽  
Stellar Collapse ◽  
Acoustic Wave Generation ◽  
Supernova Explosions ◽  
Accretion Shock ◽  
Stationary Background ◽  
Hydrodynamics Equations

ABSTRACT The convection that takes place in the innermost shells of massive stars plays an important role in the formation of core-collapse supernova explosions. Upon encountering the supernova shock, additional turbulence is generated, amplifying the explosion. In this work, we study how the convective perturbations evolve during the stellar collapse. Our main aim is to establish their physical properties right before they reach the supernova shock. To this end, we solve the linearized hydrodynamics equations perturbed on a stationary background flow. The latter is approximated by the spherical transonic Bondi accretion, while the convective perturbations are modelled as a combination of entropy and vorticity waves. We follow their evolution from large radii, where convective shells are initially located, down to small radii, where they are expected to encounter the accretion shock above the proto-neutron star. Considering typical vorticity perturbations with a Mach number ∼0.1 and entropy perturbations with magnitude ∼0.05kb/baryon, we find that the advection of these perturbations down to the shock generates acoustic waves with a relative amplitude $\delta {\rm p}/\gamma {\rm p} \lesssim 10{{\ \rm per\ cent}}$, in agreement with published numerical simulations. The velocity perturbations consist of contributions from acoustic and vorticity waves with values reaching ${\sim}10{{\ \rm per\ cent}}$ of the sound speed ahead of the shock. The perturbation amplitudes decrease with increasing ℓ and initial radii of the convective shells.

scholarly journals A shallow water analogue of asymmetric core-collapse, and neutron star kick/spin

2011 ◽  
Vol 7 (S279) ◽  
pp. 134-137
Author(s):  
Thierry Foglizzo ◽  
Frédéric Masset ◽  
Jérôme Guilet ◽  
Gilles Durand
Keyword(s):  
Neutron Star ◽  
Shallow Water ◽  
Acoustic Waves ◽  
Large Scale ◽  
Massive Stars ◽  
Core Collapse ◽  
Hydraulic Jumps ◽  
Core Collapse Supernova ◽  
Accretion Shock

AbstractMassive stars end their life with the gravitational collapse of their core and the formation of a neutron star. Their explosion as a supernova depends on the revival of a spherical accretion shock, located in the inner 200km and stalled during a few hundred milliseconds. Numerical simulations suggest that the large scale asymmetry of the neutrino-driven explosion is induced by a hydrodynamical instability named SASI. Its non radial character is able to influence the kick and the spin of the resulting neutron star. The SWASI experiment is a simple shallow water analog of SASI, where the role of acoustic waves and shocks is played by surface waves and hydraulic jumps. Distances in the experiment are scaled down by a factor one million, and time is slower by a factor one hundred. This experiment is designed to illustrate the asymmetric nature of core-collapse supernova.

scholarly journals The Status of Multi-Dimensional Core-Collapse Supernova Models

2016 ◽  
Vol 33 ◽  
Author(s):  
B. Müller
Keyword(s):  
Initial Conditions ◽  
Massive Stars ◽  
Core Collapse ◽  
Solar Mass ◽  
Convective Boundary ◽  
3D Simulations ◽  
Core Collapse Supernova ◽  
Wide Range ◽  
Supernova Explosions ◽  
The Impact

AbstractModels of neutrino-driven core-collapse supernova explosions have matured considerably in recent years. Explosions of low-mass progenitors can routinely be simulated in 1D, 2D, and 3D. Nucleosynthesis calculations indicate that these supernovae could be contributors of some lighter neutron-rich elements beyond iron. The explosion mechanism of more massive stars remains under investigation, although first 3D models of neutrino-driven explosions employing multi-group neutrino transport have become available. Together with earlier 2D models and more simplified 3D simulations, these have elucidated the interplay between neutrino heating and hydrodynamic instabilities in the post-shock region that is essential for shock revival. However, some physical ingredients may still need to be added/improved before simulations can robustly explain supernova explosions over a wide range of progenitors. Solutions recently suggested in the literature include uncertainties in the neutrino rates, rotation, and seed perturbations from convective shell burning. We review the implications of 3D simulations of shell burning in supernova progenitors for the ‘perturbations-aided neutrino-driven mechanism,’ whose efficacy is illustrated by the first successful multi-group neutrino hydrodynamics simulation of an 18 solar mass progenitor with 3D initial conditions. We conclude with speculations about the impact of 3D effects on the structure of massive stars through convective boundary mixing.

scholarly journals Core Collapse Supernova Models and Nucleosynthesis

2013 ◽  
Vol 9 (S296) ◽  
pp. 27-36
Author(s):  
Ken'ichi Nomoto
Keyword(s):  
Big Bang ◽  
Elemental Abundance ◽  
Core Collapse ◽  
Solar Abundance ◽  
First Stars ◽  
Abundance Pattern ◽  
Core Collapse Supernova ◽  
Abundance Patterns ◽  
Supernova Explosions ◽  
The Big Bang

AbstractAfter the Big Bang, production of heavy elements in the early Universe takes place in the first stars and their supernova explosions. The nature of the first supernovae, however, has not been well understood. The signature of nucleosynthesis yields of the first supernovae can be seen in the elemental abundance patterns observed in extremely metal-poor stars. Interestingly, those abundance patterns show some peculiarities relative to the solar abundance pattern, which should provide important clues to understanding the nature of early generations of supernovae. We review the recent results of the nucleosynthesis yields of massive stars. We examine how those yields are affected by some hydrodynamical effects during the supernova explosions, namely, explosion energies from those of hypernovae to faint supernovae, mixing and fallback of processed materials, asphericity, etc. Those parameters in the supernova nucleosynthesis models are constrained from observational data of supernovae and metal-poor stars.

scholarly journals Effects of Small-Scale Fluctuations of Neutrino Flux in Supernova Explosions

2005 ◽  
Vol 192 ◽  
pp. 309-314
Author(s):  
Hideki Madokoro ◽  
Tetsuya Shimizu ◽  
Yuko Motizuki
Keyword(s):  
Neutrino Flux ◽  
Explosion Energy ◽  
Small Scale ◽  
Core Collapse ◽  
Effective Mechanism ◽  
Core Collapse Supernova ◽  
Neutrino Radiation ◽  
Spherical Explosion ◽  
Supernova Explosions ◽  
Neutrino Luminosity

SummaryWe examine effects of small-scale fluctuations with angle in the neutrino radiation in core-collapse supernova explosions. As the mode number of fluctuations increases, the results approach those of spherical explosion. We conclude that global anisotropy of the neutrino radiation is the most effective mechanism of increasing the explosion energy when the total neutrino luminosity is given.

scholarly journals Standing accretion shock instability: numerical simulations of core-collapse supernova

2008 ◽  
Vol 112 (4) ◽  
pp. 042018 ◽  
Author(s):  
N Ohnishi ◽  
W Iwakami ◽  
K Kotake ◽  
S Yamada ◽  
S Fujioka ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Core Collapse ◽  
Core Collapse Supernova ◽  
Accretion Shock

scholarly journals Characterizing SASI- and convection-dominated core-collapse supernova explosions in two dimensions

2014 ◽  
Vol 440 (3) ◽  
pp. 2763-2780 ◽  
Author(s):  
Rodrigo Fernández ◽  
Bernhard Müller ◽  
Thierry Foglizzo ◽  
Hans-Thomas Janka
Keyword(s):  
Two Dimensions ◽  
Core Collapse ◽  
Core Collapse Supernova ◽  
Supernova Explosions ◽  
Convection Dominated
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