130 research outputs found
Correlated Signatures of Gravitational-Wave and Neutrino Emission in Three-Dimensional General-Relativistic Core-Collapse Supernova Simulations
We present results from general-relativistic (GR) three-dimensional (3D)
core-collapse simulations with approximate neutrino transport for three
non-rotating progenitors (11.2, 15, and 40 Msun) using different nuclear
equations of state (EOSs). We find that the combination of progenitor's higher
compactness at bounce and the use of softer EOS leads to stronger activity of
the standing accretion shock instability (SASI). We confirm previous
predications that the SASI produces characteristic time modulations both in
neutrino and gravitational-wave (GW) signals. By performing a correlation
analysis of the SASI-modulated neutrino and GW signals, we find that the
correlation becomes highest when we take into account the time-delay effect due
to the advection of material from the neutrino sphere to the proto-neutron star
core surface. Our results suggest that the correlation of the neutrino and GW
signals, if detected, would provide a new signature of the vigorous SASI
activity in the supernova core, which can be hardly seen if neutrino-convection
dominates over the SASI.Comment: 24 pages, 10 figures, Accepted for publication in Ap
Coherent Network Analysis of Gravitational Waves from Three-Dimensional Core-Collapse Supernova Models
Using predictions from three-dimensional (3D) hydrodynamics simulations of
core-collapse supernovae (CCSNe), we present a coherent network analysis to
detection, reconstruction, and the source localization of the
gravitational-wave (GW) signals. We use the {\tt RIDGE} pipeline for the
analysis, in which the network of LIGO Hanford, LIGO Livingston, VIRGO, and
KAGRA is considered. By combining with a GW spectrogram analysis, we show that
several important hydrodynamics features in the original waveforms persist in
the waveforms of the reconstructed signals. The characteristic excess in the
spectrograms originates not only from rotating core-collapse, bounce and the
subsequent ring down of the proto-neutron star (PNS) as previously identified,
but also from the formation of magnetohydrodynamics jets and non-axisymmetric
instabilities in the vicinity of the PNS. Regarding the GW signals emitted near
at the rotating core bounce, the horizon distance extends up to 18 kpc
for the most rapidly rotating 3D model in this work. Following the rotating
core bounce, the dominant source of the GW emission shifts to the
non-axisymmetric instabilities. The horizon distances extend maximally up to
40 kpc seen from the spin axis. With an increasing number of 3D models
trending towards explosion recently, our results suggest that in addition to
the best studied GW signals due to rotating core-collapse and bounce, the time
is ripe to consider how we can do science from GWs of CCSNe much more seriously
than before. Particularly the quasi-periodic signals due to the
non-axisymmetric instabilities and the detectability should deserve further
investigation to elucidate the inner-working of the rapidly rotating CCSNe.Comment: PRD in pres
Linear response theory in the continuum for deformed nuclei: Green's function vs. time-dependent Hartree-Fock with the absorbing-boundary condition
The continuum random-phase approximation is extended to the one applicable to
deformed nuclei. We propose two different approaches. One is based on the use
of the three dimensional (3D) Green's function and the other is the
small-amplitude TDHF with the absorbing-boundary condition. Both methods are
based on the 3D Cartesian grid representation and applicable to systems without
any symmetry on nuclear shape. The accuracy and identity of these two methods
are examined with the BKN interaction. Using the full Skyrme energy functional
in the small-amplitude TDHF approach, we study the isovector giant dipole
states in the continuum for O-16 and for even-even Be isotopes.Comment: 15 pages, 8 figure
Cross-Correlation between UHECR Arrival Distribution and Large-Scale Structure
We investigate correlation between the arrival directions of
ultra-high-energy cosmic rays (UHECRs) and the large-scale structure (LSS) of
the Universe by using statistical quantities which can find the angular scale
of the correlation. The Infrared Astronomical Satellite Point Source Redshift
Survey (IRAS PSCz) catalog of galaxies is adopted for LSS. We find a positive
correlation of the highest energy events detected by the Pierre Auger
Observatory (PAO) with the IRAS galaxies inside within the angular
scale of . This positive correlation observed in the southern
sky implies that a significant fraction of the highest energy events comes from
nearby extragalactic objects. We also analyze the data of the Akeno Giant Air
Shower Array (AGASA) which observed the northern hemisphere, but the obvious
signals of positive correlation with the galaxy distribution are not found.
Since the exposure of the AGASA is smaller than the PAO, the cross-correlation
in the northern sky should be tested using a larger number of events detected
in the future. We also discuss the correlation using the all-sky combined data
sets of both the PAO and AGASA, and find a significant correlation within . These angular scales can constrain several models of intergalactic
magnetic field. These cross-correlation signals can be well reproduced by a
source model in which the distribution of UHECR sources is related to the IRAS
galaxies.Comment: 21 pages,7 figure
E22Δ Mutation in Amyloid β-Protein Promotes β-Sheet Transformation, Radical Production, and Synaptotoxicity, But Not Neurotoxicity
Oligomers of 40- or 42-mer amyloid β-protein (Aβ40, Aβ42) cause cognitive decline and synaptic dysfunction in Alzheimer's disease. We proposed the importance of a turn at Glu22 and Asp23 of Aβ42 to induce its neurotoxicity through the formation of radicals. Recently, a novel deletion mutant at Glu22 (E22Δ) of Aβ42 was reported to accelerate oligomerization and synaptotoxicity. To investigate this mechanism, the effects of the E22Δ mutation in Aβ42 and Aβ40 on the transformation of β-sheets, radical production, and neurotoxicity were examined. Both mutants promoted β-sheet transformation and the formation of radicals, while their neurotoxicity was negative. In contrast, E22P-Aβ42 with a turn at Glu22 and Asp23 exhibited potent neurotoxicity along with the ability to form radicals and potent synaptotoxicity. These data suggest that conformational change in E22Δ-Aβ is similar to that in E22P-Aβ42 but not the same, since E22Δ-Aβ42 exhibited no cytotoxicity, unlike E22P-Aβ42 and wild-type Aβ42
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