Three-Dimensional Boltzmann Hydro Code for Core Collapse in Massive Stars. I. Special Relativistic Treatments

Iwakami

et al. 2017

ApJ

We investigate the criterion for the acoustic mechanism to work successfully in core-collapse supernovae. The acoustic mechanism is an alternative to the neutrino-heating mechanism. It was proposed by Burrows et al., whoclaimedthat acoustic waves emitted by g-mode oscillations in proto-neutron stars (PNS) energize a stalled shock wave and eventuallyinduce an explosion. Previous works mainly studiedto whichextent the g-modes are excited in the PNS. In this paper, on the other hand, we investigatehow strong the acoustic wave needs tobe if it were to revive a stalled shock wave. By adding the acoustic power as a new axis, we draw a critical surface, which is an extension of the critical curve commonly employed in the context of neutrino heating. We perform both 1D and 2D parametrized simulations, in which we inject acoustic waves from the inner boundary. In order to quantify the power of acoustic waves, we usethe extended Myerstheory to take neutrino reactions into proper account. We find for the 1D simulations that rather large acoustic powers are required to relaunch the shock wave, since the additional heating provided by the secondary shocks developed from acoustic waves is partially canceled by the neutrino cooling that is also enhanced. In 2D, the required acoustic powers are consistent with those of Burrows et al. Our results seem to imply, however, that it is the sum of neutrino heating and acoustic powers that matters for shock revival.

Section: Methodsmentioning

confidence: 99%

A Parametric Study of the Acoustic Mechanism for Core-collapse Supernovae

Harada

Iwakami

et al. 2017

ApJ

“…Then, we need to take into account the transport of neutrinos appropriately. We thus employ the one-dimensional hydrodynamical code with a Boltzmann solver developed by Nagakura et al (2014Nagakura et al ( , 2016 to follow the evolution of the core collapse. The hydrodynamics solver is explicit and has second-order accuracy in both space and time, based on the so-called central scheme (Kurganov & Tadmor 2000;Nagakura & Yamada 2008;Nagakura et al 2011); spherical coordinates are adopted; and Newtonian selfgravity is taken into account.…”

Section: Core Collapsementioning

confidence: 99%

Neutrino Emissions in All Flavors up to the Pre-bounce of Massive Stars and the Possibility of Their Detections

Kato

Furusawa

et al. 2017

ApJ

Self Cite

This paper is a sequel to our 2015 paper, Kato et al., which calculated the luminosities and spectra of electron-type anti-neutrinos ( e n ) from the progenitors of core-collapse supernovae. Expecting that the capability to detect electron-type neutrinos ( e n ) will increase dramatically with the emergence of liquid-argon detectors such as DUNE, we broaden the scope in this study to include all flavors of neutrinos emitted from the pre-bounce phase. We pick up three progenitor models of electron capture supernovae (ECSNe) and iron-core collapse supernovae (FeCCSNe). We find that the number luminosities reach ∼10 57 s -1 and ∼10 53 s -1 at maximum for e n and e n , respectively. We also estimate the numbers of detection events at terrestrial neutrino detectors including DUNE, taking flavor oscillations into account and assuming the distance to the progenitors to be 200 pc. It is demonstrated that e n from the ECSN progenitor will be undetected at almost all detectors, whereas we will be able to observe 15,900 e n at DUNE for the inverted mass hierarchy. From the FeCCSN progenitors, the number of e n events will be largest for JUNO, 200-900 e n , depending on the mass hierarchy, whereas the number of e n events at DUNE is 2100  for the inverted mass hierarchy. These results imply that the detection of e n is useful to distinguish progenitors of FeCCSNe from those of ECSNe, while e n will provide us with detailed information on the collapse phase regardless of the type and mass of the progenitor.

“…As for the input physics, our current Boltzmann-Hydro code has updated some treatments of microphysics from Sumiyoshi & Yamada (2012), Nagakura et al (2014). One of them is an incorporation of the multi-nuclear species equation of state (EOS) by Furusawa et al (2011.…”

Section: Numerical Setup and Input Physicsmentioning

confidence: 99%

“…The 4-momentum of neutrino is also projected on m(ˆ) e . Then the energy shift and aberration are determined by the Doppler factor given above and our SR formulation can be directly passed over to the GRextended code (see Section4 in Nagakura et al 2014). …”

mentioning

confidence: 99%

Three-dimensional Boltzmann-Hydro Code for Core-collapse in Massive Stars. II. The Implementation of Moving-mesh for Neutron Star Kicks

Iwakami

Furusawa

et al. 2017

ApJS

Self Cite

We present a newly developed moving-mesh technique for the multi-dimensional Boltzmann-Hydro code for the simulation of core-collapse supernovae (CCSNe). What makes this technique different from others is the fact that it treats not only hydrodynamics but also neutrino transfer in the language of the 3+1 formalism of general relativity (GR), making use of the shift vector to specify the time evolution of the coordinate system. This means that the transport part of our code is essentially general relativistic, although in this paper it is applied only to the moving curvilinear coordinates in the flat Minknowski spacetime, since the gravity part is still Newtonian. The numerical aspect of the implementation is also described in detail. Employing the axisymmetric two-dimensional version of the code, we conduct two test computations: oscillations and runaways of proto-neutron star (PNS). We show that our new method works fine, tracking the motions of PNS correctly. We believe that this is a major advancement toward the realistic simulation of CCSNe.