79 research outputs found
Light curve analysis of ordinary type IIP supernovae based on neutrino-driven explosion simulations in three dimensions
Type II-plateau supernovae (SNe IIP) are the most numerous subclass of
core-collapse SNe originating from massive stars. In the framework of the
neutrino-driven explosion mechanism, we study the SN outburst properties for a
red supergiant progenitor model and compare the corresponding light curves with
observations of the ordinary Type IIP SN 1999em. Three-dimensional (3D)
simulations of (parametrically triggered) neutrino-driven explosions are
performed with the (explicit, finite-volume, Eulerian, multifluid
hydrodynamics) code PROMETHEUS, using a presupernova model of a 15 Msun star as
initial data. At approaching homologous expansion, the hydrodynamical and
composition variables of the 3D models are mapped to a spherically symmetric
configuration, and the simulations are continued with the (implicit, Lagrangian
radiation-hydrodynamics) code CRAB to follow the blast-wave evolution during
the SN outburst. Our 3D neutrino-driven explosion model with an explosion
energy of about 0.5x10^51 erg produces Ni-56 in rough agreement with the amount
deduced from fitting the radioactively powered light-curve tail of SN 1999em.
The considered presupernova model, 3D explosion simulations, and light-curve
calculations can explain the basic observational features of SN 1999em, except
for those connected to the presupernova structure of the outer stellar layers.
Our 3D simulations show that the distribution of Ni-rich matter in velocity
space is asymmetric with a strong dipole component that is consistent with the
observations of SN 1999em. The monotonic luminosity decline from the plateau to
the radioactive tail in ordinary SNe IIP is a manifestation of the intense
turbulent mixing at the He/H composition interface.Comment: 16 pages, 13 figures, 2 tables; added figure, discussions, and
references; accepted for publication in Ap
SASI Activity in Three-Dimensional Neutrino-Hydrodynamics Simulations of Supernova Cores
The relevance of the standing accretion shock instability (SASI) compared to
neutrino-driven convection in three-dimensional (3D) supernova-core
environments is still highly controversial. Studying a 27 Msun progenitor, we
demonstrate, for the first time, that violent SASI activity can develop in 3D
simulations with detailed neutrino transport despite the presence of
convection. This result was obtained with the Prometheus-Vertex code with the
same sophisticated neutrino treatment so far used only in 1D and 2D models.
While buoyant plumes initially determine the nonradial mass motions in the
postshock layer, bipolar shock sloshing with growing amplitude sets in during a
phase of shock retraction and turns into a violent spiral mode whose growth is
only quenched when the infall of the Si/SiO interface leads to strong shock
expansion in response to a dramatic decrease of the mass accretion rate. In the
phase of large-amplitude SASI sloshing and spiral motions, the postshock layer
exhibits nonradial deformation dominated by the lowest-order spherical
harmonics (l=1, m=0,-1,+1) in distinct contrast to the higher multipole
structures associated with neutrino-driven convection. We find that the SASI
amplitudes, shock asymmetry, and nonradial kinetic energy in 3D can exceed
those of the corresponding 2D case during extended periods of the evolution. We
also perform parametrized 3D simulations of a 25 Msun progenitor, using a
simplified, gray neutrino transport scheme, an axis-free Yin-Yang grid, and
different amplitudes of random seed perturbations. They confirm the importance
of the SASI for another progenitor, its independence of the choice of spherical
grid, and its preferred growth for fast accretion flows connected to small
shock radii and compact proto-neutron stars as previously found in 2D setups.Comment: 17 pages, 10 figures, accepted by The Astrophysical Journa
Three-dimensional Models of Core-collapse Supernovae From Low-mass Progenitors With Implications for Crab
We present 3D full-sphere supernova simulations of non-rotating low-mass (~9
Msun) progenitors, covering the entire evolution from core collapse through
bounce and shock revival, through shock breakout from the stellar surface,
until fallback is completed several days later. We obtain low-energy explosions
[~(0.5-1.0)x 10^{50} erg] of iron-core progenitors at the low-mass end of the
core-collapse supernova (LMCCSN) domain and compare to a super-AGB (sAGB)
progenitor with an oxygen-neon-magnesium core that collapses and explodes as
electron-capture supernova (ECSN). The onset of the explosion in the LMCCSN
models is modelled self-consistently using the Vertex-Prometheus code, whereas
the ECSN explosion is modelled using parametric neutrino transport in the
Prometheus-HOTB code, choosing different explosion energies in the range of
previous self-consistent models. The sAGB and LMCCSN progenitors that share
structural similarities have almost spherical explosions with little metal
mixing into the hydrogen envelope. A LMCCSN with less 2nd dredge-up results in
a highly asymmetric explosion. It shows efficient mixing and dramatic shock
deceleration in the extended hydrogen envelope. Both properties allow fast
nickel plumes to catch up with the shock, leading to extreme shock deformation
and aspherical shock breakout. Fallback masses of <~5x10^{-3} Msun have no
significant effects on the neutron star (NS) masses and kicks. The anisotropic
fallback carries considerable angular momentum, however, and determines the
spin of the newly-born NS. The LMCCSNe model with less 2nd dredge-up results in
a hydrodynamic and neutrino-induced NS kick of >40 km/s and a NS spin period of
~30 ms, both not largely different from those of the Crab pulsar at birth.Comment: 47 pages, 27 figures, 6 tables; minor revisions, accepted by MNRA
Gravitational Wave Memory from Core-Collapse Supernovae
Memory is a low frequency signal produced in asymmetric core-collapse supernova explosions. The memory is dependent on three facets in the supernovae: the matter emission, the anisotropic neutrino emission, and the neutrino energy density. This low frequency component can be modeled by applying a long-term cosine to the end of simulated explosions. In order to make a detection (at either ground-based or space-based detectors) a complete understanding of the transfer functions at low frequencies is required, which involves the motion of the ground and harmonic oscillations from the suspensions. The memory is investigated by comparing a the previously mentioned toy model and the spherical harmonic decomposition of numerical simulation. Here we present our initial investigation of the toy model and numerical simulations
An axis-free overset grid in spherical polar coordinates for simulating 3D self-gravitating flows
A type of overlapping grid in spherical coordinates called the Yin-Yang grid
is successfully implemented into a 3D version of the explicit Eulerian
grid-based code PROMETHEUS including self-gravity. The modified code
successfully passed several standard hydrodynamic tests producing results which
are in very good agreement with analytic solutions. Moreover, the solutions
obtained with the Yin-Yang grid exhibit no peculiar behaviour at the boundary
between the two grid patches. The code has also been successfully used to model
astrophysically relevant situations, namely equilibrium polytropes, a
Taylor-Sedov explosion, and Rayleigh-Taylor instabilities. According to our
results, the usage of the Yin-Yang grid greatly enhances the suitability and
efficiency of 3D explicit Eulerian codes based on spherical polar coordinates
for astrophysical flows.Comment: 15 pages, 17 figures, 2 tables, accepted for publication in A&
Modeling Core-Collapse Supernovae Gravitational-Wave Memory in Laser Interferometric Data
We study the properties of the gravitational wave (GW) emission between Hz and Hz (which we refer to as low-frequency emission) from core-collapse supernovae, in the context of studying such signals in laser interferometric data as well as performing multi-messenger astronomy. We pay particular attention to the GW linear memory, which is when the signal amplitude does not return to zero after the GW burst. Based on the long term simulation of a core-collapse supernova of a solar-metallicity star with a zero-age main sequence mass of 15 solar masses, we discuss the spectral properties, the memory's dependence on observer position and the polarization of low-frequency GWs from slowly non (or slowly) rotating core-collapse supernovae. We make recommendations on the angular spacing of the orientations needed to properly produce results that are averaged over multiple observer locations by investigating the angular dependence of the GW emission. We propose semi-analytical models that quantify the relationship between the bulk motion of the supernova shock-wave and the GW memory amplitude. We discuss how to extend neutrino generated GW signals from numerical simulations that were terminated before the neutrino emission has subsided. We discuss how the premature halt of simulations and the non-zero amplitude of the GW memory can induce artefacts during the data analysis process. Lastly, we also investigate potential solutions and issues in the use of taperings for both ground and space-based interferometers
The fully developed remnant of a neutrino-driven supernova: Evolution of ejecta structure and asymmetries in SNR Cassiopeia A
Abridged. We aim at exploring to which extent the remnant keeps memory of the
asymmetries that develop stochastically in the neutrino-heating layer due to
hydrodynamic instabilities (e.g., convective overturn and the standing
accretion shock instability) during the first second after core bounce. We
coupled a 3D HD model of a neutrino-driven SN explosion with 3D MHD/HD
simulations of the remnant formation. The simulations cover 2000 years of
expansion and include all physical processes relevant to describe the
complexities in the SN evolution and the subsequent interaction of the stellar
debris with the wind of the progenitor star. The interaction of large-scale
asymmetries left from the earliest phases of the explosion with the reverse
shock produces, at the age of ~years, an ejecta structure and a
remnant morphology which are remarkably similar to those observed in Cas A.
Small-scale structures in the large-scale Fe-rich plumes created during the
initial stages of the SN, combined with HD instabilities that develop after the
passage of the reverse shock, naturally produce a pattern of ring- and
crown-like structures of shocked ejecta. The consequence is a spatial inversion
of the ejecta layers with Si-rich ejecta being physically interior to Fe-rich
ejecta. The full-fledged remnant shows voids and cavities in the innermost
unshocked ejecta resulting from the expansion of Fe-rich plumes and their
inflation due to the decay of radioactive species. The asymmetric distributions
of Ti and Fe and their abundance ratio are both compatible with
those inferred from high-energy observations of Chandra and NuSTAR. The main
asymmetries observed in the ejecta distribution of Cas A can be explained by
the interaction of the reverse shock with the large-scale asymmetries that
developed from stochastic processes that originate during the first seconds of
the SN blast.Comment: 33 pages, 29 figures, 1 Table, 4 movies, 3 interactive graphics,
accepted for publication on A&A, high quality figures will be available on
the published pape
The fully developed remnant of a neutrino-driven supernova: Evolution of ejecta structure and asymmetries in SNR Cassiopeia A
Context. The remnants of core-collapse supernovae (SNe) are probes of the physical processes associated with their parent SNe. Aims. Here we aim to explore to which extent the remnant keeps memory of the asymmetries that develop stochastically in the neutrino-heating layer due to hydrodynamic instabilities (e.g., convective overturn and the standing accretion shock instability; SASI) during the first second after core bounce. Methods. We coupled a three-dimensional (3D) hydrodynamic model of a neutrino-driven SN explosion, which has the potential to reproduce the observed morphology of the Cassiopeia A (Cas A) remnant, with 3D (magneto)-hydrodynamic simulations of the remnant formation. The simulations cover ≈2000 yr of expansion and include all physical processes relevant to describe the complexities in the SN evolution and the subsequent interaction of the stellar debris with the wind of the progenitor star. Results. The interaction of large-scale asymmetries left from the earliest phases of the explosion with the reverse shock produces, at the age of ≈350 yr, an ejecta structure and a remnant morphology which are remarkably similar to those observed in Cas A. Small-scale structures in the large-scale Fe-rich plumes that were created during the initial stages of the SN, combined with hydrodynamic instabilities that develop after the passage of the reverse shock, naturally produce a pattern of ring-and crown-like structures of shocked ejecta. The consequence is a spatial inversion of the ejecta layers with Si-rich ejecta being physically interior to Fe-rich ejecta. The full-fledged remnant shows voids and cavities in the innermost unshocked ejecta, which are physically connected with ring-like features of shocked ejecta in the main shell in most cases, resulting from the expansion of Fe-rich plumes and their inflation due to the decay of radioactive species. The asymmetric distributions of 44Ti and 56Fe, which are mostly concentrated in the northern hemisphere, and pointing opposite to the kick velocity of the neutron star, as well as their abundance ratio are both compatible with those inferred from high-energy observations of Chandra and NuSTAR. Finally, the simulations show that the fingerprints of the SN can still be visible ≈2000 yr after the explosion. Conclusions. The main asymmetries and features observed in the ejecta distribution of Cas A can be explained by the interaction of the reverse shock with the initial large-scale asymmetries that developed from stochastic processes (e.g., convective overturn and SASI activity) that originate during the first seconds of the SN blast
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