scholarly journals Spectropolarimetry of stripped-envelope supernovae: observations and modelling

2017 ◽  
Vol 375 (2105) ◽  
pp. 20160273 ◽  
Author(s):  
Masaomi Tanaka
Keyword(s):  
Large Scale ◽  
Massive Stars ◽  
Three Dimensional ◽  
Core Collapse ◽  
Ion Distribution ◽  
Typical Size ◽  
Cassiopeia A ◽  
Accretion Shock

Spectropolarimetry is one of the most powerful methods to study the multi-dimensional geometry of supernovae (SNe). We present a brief summary of the spectropolarimetric observations of stripped-envelope core-collapse SNe. Observations indicate that stripped-envelope SNe generally have a non-axisymmetric ion distribution in the ejecta. Three-dimensional clumpy geometry nicely explains the observed properties. A typical size of the clumps deduced from observations is relatively large: 25% of the photosphere. Such a large-scale clumpy structure is similar to that observed in Cassiopeia A, and suggests that large-scale convection or standing accretion shock instability takes place at the onset of the explosion. This article is part of the themed issue ‘Bridging the gap: from massive stars to supernovae’.

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 Autopsy of the Supernova Remnant Cassiopeia A

2013 ◽  
Vol 9 (S296) ◽  
pp. 155-159
Author(s):  
Dan Milisavljevic ◽  
Robert A. Fesen
Keyword(s):  
Large Scale ◽  
Supernova Remnant ◽  
Three Dimensional ◽  
Radioactive Material ◽  
Core Collapse ◽  
Common Phenomenon ◽  
Cassiopeia A ◽  
Circular Rings ◽  
Cas A ◽  
Emission Line Profile

AbstractThree-dimensional kinematic reconstructions of optically emitting ejecta in the young Galactic supernova remnant Cassiopeia A (Cas A) are discussed. The reconstructions encompass the remnant's faint outlying ejecta knots, including the exceptionally high-velocity NE and SW streams of debris often referred to as ‘jets’. The bulk of Cas A's ejecta are arranged in several circular rings with diameters between approximately 30″ (0.5 pc) and 2′ (2 pc). We suggest that similar large-scale ejecta rings may be a common phenomenon of young core-collapse remnants and may explain lumpy emission line profile substructure sometimes observed in spectra of extragalactic core-collapse supernovae years after explosion. A likely origin for these large ejecta rings is post-explosion input of energy from plumes of radioactive 56Ni-rich ejecta that rise, expand, and compress non-radioactive material to form bubble-like structures.

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

2017 ◽  
Vol 229 (2) ◽  
pp. 42 ◽  
Author(s):  
Hiroki Nagakura ◽  
Wakana Iwakami ◽  
Shun Furusawa ◽  
Kohsuke Sumiyoshi ◽  
Shoichi Yamada ◽  
...  
Keyword(s):  
Neutron Star ◽  
Massive Stars ◽  
Three Dimensional ◽  
Moving Mesh ◽  
Core Collapse

GRAVITATIONAL COLLAPSE OF MASSIVE STARS AS A PROBE INTO HOT DENSE MATTER

2008 ◽  
Vol 23 (27n30) ◽  
pp. 2443-2450 ◽  
Author(s):  
SHOICHI YAMADA
Keyword(s):  
Equation Of State ◽  
Gravitational Collapse ◽  
Nuclear Physics ◽  
Massive Stars ◽  
Dense Matter ◽  
High Energy ◽  
Compact Objects ◽  
Core Collapse ◽  
Accretion Shock ◽  
Very High

Nuclear physics is an indispensable input for the investigation of high energy astrophysical phenomena involving compact objects. In this paper I take a gravitational collapse of massive stars as an example and show how the macroscopic dynamics is influenced by the properties of nuclei and nuclear matter. I will discuss two topics that are rather independent of each other. The first one is the interplay of neutrino-nuclei inelastic scatterings and the standing accretion shock instability in the core of core collapse supernovae and the second is concerning the neutrino emissions from black hole formations and their dependence on the equation of state at very high densities. In the latter, I will also demonstrate that future astronomical observations might provide us with valuable information on the equation of state of hot dense matter.

scholarly journals The mechanism(s) of core-collapse supernovae

2017 ◽  
Vol 375 (2105) ◽  
pp. 20160271 ◽  
Author(s):  
Sean M. Couch
Keyword(s):  
Massive Stars ◽  
Three Dimensional ◽  
Short Review ◽  
Core Collapse ◽  
The Impact ◽  
Three Dimensional Simulations

Core-collapse supernovae (CCSNe) are the explosions that attend the deaths of massive stars. Despite decades of research, several aspects of the mechanism that drives these explosions remain uncertain and the subjects of continued investigation. In this short review, I will give an overview of the CCSN mechanism and current research in the field. In particular, I will focus on recent results from three-dimensional simulations and the impact of turbulence and detailed non-spherical progenitor structure on CCSNe. This contribution is based on a talk given at the ‘Bridging the Gap’ workshop at Chicheley Hall on 2 June 2016. This article is part of the themed issue ‘Bridging the gap: from massive stars to supernovae’.

scholarly journals Magnetic Fields in Stars: Origin and Impact

2013 ◽  
Vol 9 (S302) ◽  
pp. 1-9 ◽  
Author(s):  
N. Langer
Keyword(s):  
Magnetic Fields ◽  
Differential Rotation ◽  
Large Scale ◽  
Massive Stars ◽  
High Mass ◽  
Binary Interaction ◽  
Small Scale ◽  
Core Collapse ◽  
Intermediate Mass ◽  
Supernova Explosions

AbstractVarious types of magnetic fields occur in stars: small scale fields, large scale fields, and internal toroidal fields. While the latter may be ubiquitous in stars due to differential rotation, small scale fields (spots) may be associated with envelop convection in all low and high mass stars. The stable large scale fields found in only about 10% of intermediate mass and massive stars may be understood as a consequence of dynamical binary interaction, e.g., the merging of two stars in a binary. We relate these ideas to magnetic fields in white dwarfs and neutron stars, and to their role in core-collapse and thermonuclear supernova explosions.

scholarly journals Core-collapse supernova neutrino emission and detection informed by state-of-the-art three-dimensional numerical models

2020 ◽  
Vol 500 (1) ◽  
pp. 696-717 ◽  
Author(s):  
Hiroki Nagakura ◽  
Adam Burrows ◽  
David Vartanyan ◽  
David Radice
Keyword(s):  
Numerical Models ◽  
Three Dimensional ◽  
Neutrino Energy ◽  
Reconstruction Technique ◽  
Core Collapse ◽  
Cumulative Number ◽  
Core Collapse Supernova ◽  
Interesting Correlation ◽  
Time Variations ◽  
Accretion Shock

ABSTRACT Based on our recent three-dimensional core-collapse supernova (CCSN) simulations including both exploding and non-exploding models, we study the detailed neutrino signals in representative terrestrial neutrino observatories, namely Super-Kamiokande (Hyper-Kamiokande), DUNE, JUNO, and IceCube. We find that the physical origin of difference in the neutrino signals between 1D and 3D is mainly proto-neutron-star convection. We study the temporal and angular variations of the neutrino signals and discuss the detectability of the time variations driven by the spiral standing accretion shock instability (spiral SASI) when it emerges for non-exploding models. In addition, we determine that there can be a large angular asymmetry in the event rate (${\gtrsim} 50 {{\ \rm per\ cent}}$), but the time-integrated signal has a relatively modest asymmetry (${\lesssim} 20 {{\ \rm per\ cent}}$). Both features are associated with the lepton-number emission self-sustained asymmetry and the spiral SASI. Moreover, our analysis suggests that there is an interesting correlation between the total neutrino energy (TONE) and the cumulative number of neutrino events in each detector, a correlation that can facilitate data analyses of real observations. We demonstrate the retrieval of neutrino energy spectra for all flavours of neutrino by applying a novel spectrum reconstruction technique to the data from multiple detectors. We find that this new method is capable of estimating the TONE within the error of ∼20 per cent if the distance to the CCSN is ≲6 kpc.

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