The Evolution towards Electron-capture Supernovae: the Flame Propagation and the Pre-bounce Electron-neutrino Radiation. (arXiv:1812.07175v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Takahashi_K/0/1/0/all/0/1">K. Takahashi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sumiyoshi_K/0/1/0/all/0/1">K. Sumiyoshi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yamada_S/0/1/0/all/0/1">S. Yamada</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Umeda_H/0/1/0/all/0/1">H. Umeda</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yoshida_T/0/1/0/all/0/1">T. Yoshida</a>
A critical mass ONe core with a high ignition density is considered to end in
gravitational collapse leading to neutron star formation. Being distinct from a
Fe core collapse, the final evolution involves combustion flame propagation, in
which complex phase transition from ONe elements into the
nuclear-statistical-equilibrium (NSE) state takes place. We simulate the core
evolution from the O+Ne ignition until the bounce shock penetrates the whole
core, using a state-of-the-art 1D Lagrangian neutrino-radiation-hydrodynamic
code, in which important nuclear burning, electron capture, and neutrino
reactions are taken into account. Special care is also taken in making a stable
initial condition by importing the stellar EOS, which is used for the
progenitor evolution calculation, and by improving the remapping process. We
find that the central ignition leads to intense $nu_e$ radiation with
$L_{nu_e} gtrsim 10^{51}$ erg s$^{-1}$ powered by fast electron captures onto
NSE isotopes. This pre-bounce $nu_e$ radiation heats the surroundings by the
neutrino-electron scattering, which acts as a new driving mechanism of the
flame propagation together with the adiabatic contraction. The resulting flame
velocity of $sim10^8$ cm s$^{-1}$ will be more than one-order-of-magnitude
faster than that of laminar flame driven by heat conduction. We also find that
the duration of the pre-bounce $nu_e$ radiation phase depends on the degree of
the core hydrostatic/dynamical stability. Therefore, the future detection of
the pre-bounce neutrino is important not only to discriminate the ONe core
collapse from the Fe core collapse but also to constrain the progenitor
hydrodynamical stability.
A critical mass ONe core with a high ignition density is considered to end in
gravitational collapse leading to neutron star formation. Being distinct from a
Fe core collapse, the final evolution involves combustion flame propagation, in
which complex phase transition from ONe elements into the
nuclear-statistical-equilibrium (NSE) state takes place. We simulate the core
evolution from the O+Ne ignition until the bounce shock penetrates the whole
core, using a state-of-the-art 1D Lagrangian neutrino-radiation-hydrodynamic
code, in which important nuclear burning, electron capture, and neutrino
reactions are taken into account. Special care is also taken in making a stable
initial condition by importing the stellar EOS, which is used for the
progenitor evolution calculation, and by improving the remapping process. We
find that the central ignition leads to intense $nu_e$ radiation with
$L_{nu_e} gtrsim 10^{51}$ erg s$^{-1}$ powered by fast electron captures onto
NSE isotopes. This pre-bounce $nu_e$ radiation heats the surroundings by the
neutrino-electron scattering, which acts as a new driving mechanism of the
flame propagation together with the adiabatic contraction. The resulting flame
velocity of $sim10^8$ cm s$^{-1}$ will be more than one-order-of-magnitude
faster than that of laminar flame driven by heat conduction. We also find that
the duration of the pre-bounce $nu_e$ radiation phase depends on the degree of
the core hydrostatic/dynamical stability. Therefore, the future detection of
the pre-bounce neutrino is important not only to discriminate the ONe core
collapse from the Fe core collapse but also to constrain the progenitor
hydrodynamical stability.
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