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we perform an extensive study of the correlations between the neutrino-nucleon inverse mean free paths (imfps) and the underlying equation of states (eoss). strong interaction uncertainties in the neutrino mean free path are investigated in different density regimes. the nucleon effective mass, the nucleon chemical potentials, and the residual interactions in the medium play an important role in determining neutrino-nucleon interactions in a density-dependent manner. we study how the above quantities are constrained by an eos consistent with (i) nuclear mass measurements, (ii) proton-proton scattering phase shifts, and (iii) neutron star observations. we then study the uncertainties of both the charged current and the neutral current neutrino-nucleon inverse mean free paths due to the variation of these quantities, using the hartree-fock+random phase approximation method. finally, we calculate the pearson correlation coefficients between (i) the eos-based quantities and the eos-based quantities; (ii) the eos-based quantities and the imfps; (iii) the imfps and the imfps. we find a strong impact of residual interactions on neutrino opacity in the spin and spin-isospin channels, which are not well constrained by current nuclear modelings. | uncertainty quantification for neutrino opacities in core-collapse supernovae and neutron star mergers |
a quark-nova is a hypothetical stellar evolution branch where a neutron star converts explosively into a quark star. here, we discuss the intimate coupling between the micro-physics and macro-physics of the quark-nova and provide a prescription for how to couple the burn-ud code to the stellar evolution code in order to simulate neutron-star-to-quark-star burning at stellar scales and estimate the resulting energy release and ejecta. once formed, the thermal evolution of the proto-quark star follows. we found much higher peak neutrino luminosities (>1055 erg/s) and a higher energy neutrino (i.e., harder) spectrum than previous stellar evolution studies of proto-neutron stars. we derived the neutrino counts that observatories such as super-kamiokande-iii and halo-ii should expect and suggest how these can differentiate between a supernova and a quark-nova. due to the high peak neutrino luminosities, neutrino pair annihilation can deposit as much as 1052 ergs in kinetic energy in the matter overlaying the neutrinosphere, yielding relativistic quark-nova ejecta. we show how the quark-nova could help us understand many still enigmatic high-energy astrophysical transients, such as super-luminous supernovae, gamma-ray bursts and fast radio bursts. | the macro-physics of the quark-nova: astrophysical implications |
a detailed study of the charged-current supernova electron neutrino and electron antineutrino scattering off the stable even-mass lead isotopes a =204 , 206, and 208 is reported in this work. the proton-neutron quasiparticle random-phase approximation (pnqrpa) is adopted to construct the nuclear final and initial states. three different skyrme interactions are tested for their isospin and spin-isospin properties and then applied to produce (anti)neutrino-nucleus scattering cross sections for (anti)neutrino energies below 80 mev. realistic estimates of the nuclear responses to supernova (anti)neutrinos are computed by folding the computed cross sections with a two-parameter fermi-dirac distribution of the electron (anti)neutrino energies. the computed cross sections are compared with earlier calculations and the analyses are extended to take into account the effects coming from the neutrino oscillations. | theoretical estimates of supernova-neutrino cross sections for the stable even-even lead isotopes: charged-current reactions |
in order to explain the recently reported peak at 3.55 kev in the galactic x-ray spectrum, we propose a simple model. in this model, the standard model is extended by including a neutral spin-3/2 vector-like fermion that transforms like a singlet under sm gauge group. this 7.1 kev spin-3/2 fermion is considered to comprise a portion of the observed dark matter. its decay into a neutrino and a photon with decay life commensurate with the observed data, fits the relic dark matter density and obeys the astrophysical constraints from the supernova cooling. | anomalous x-ray galactic signal from 7.1 kev spin-3/2 dark matter decay |
future neutrino detectors will obtain high-statistics data from a nearby core-collapse supernova. we study the mixing with ev-mass sterile neutrinos in a supernova environment and its effects on the active neutrino fluxes as detected by hyper-kamiokande and icecube. using a markov chain monte carlo analysis, we make projections for how accurately these experiments will measure the active-sterile mixing angle θs given that there are substantial uncertainties on the expected luminosity and spectrum of active neutrinos from a galactic supernova burst. we find that hyper-kamiokande can reconstruct the sterile neutrino mixing and mass in many different situations, provided the neutrino luminosity of the supernova is known precisely. crucially, we identify a degeneracy between the mixing angle and the overall neutrino luminosity of the supernova. this means that it will only be possible to determine the luminosity if the presence of sterile neutrinos with θs gtrsim 0.1o can be ruled out independently. we discuss ways in which this degeneracy may be broken in the future. | prospects for detecting ev-scale sterile neutrinos from a galactic supernova |
supernova relic neutrino (srn) has not been observed yet because of its low event rate and high background. by adding gadolinium into water cherenkov detector, inverse beta decay will have two signals, the prompt one is positron signal and the delayed one is a ~8 mev gamma cascade from neutron capture on gadolinium. by this way, background for srn can be largely reduced by detecting prompt and delayed signals coincidently, and super-k will also have the ability to distinguish neutrino and anti-neutrino. sk-gd is a r&d project proposed to dissolve gadolinium into super-k. as a part of it, egads, a 200 ton water cherenkov detector was built in kamioka mine. current status of sk-gd project and the physics work being performed in egads will be presented here. | current status of sk-gd project and egads |
we examine the sensitivity of neutrino emission to stellar evolution models for a 15 m⊙ progenitor, paying particular attention to a phase prior to the collapse. we demonstrate that the number luminosities in both electron-type neutrinos (νe) and their antipartners ( $\bar{\nu }_\mathrm{ e}$ ) differ by more than an order of magnitude by changing spatial resolutions and nuclear network sizes on stellar evolution models. we also develop a phenomenological model to capture the essential trend of the diversity, in which neutrino luminosities are expressed as a function of central density, temperature, and electron fraction. in the analysis, we show that the neutrino luminosity can be well characterized by these central quantities. this analysis also reveals that the most influential quantity to the time evolution of νe luminosity is matter density, while it is temperature for $\bar{\nu }_\mathrm{ e}$ . these qualitative trends will be useful and applicable to constrain the physical states of progenitors at the final stages of stellar evolution from future neutrino observations, although more detailed systematic studies including various mass progenitors are required to assess the applicability. | the sensitivity of presupernova neutrinos to stellar evolution models |
the measurement of the period and period derivative, and the canonical model of dipole radiation have provided a method to estimate the low superficial magnetic fields in the so-called central compact objects (ccos). in the present work, a scenario is introduced in order to explain the magnetic behavior of such ccos. based on magnetohydrodynamic simulations of the post core-collapse supernova phase during the hypercritical accretion episode, we argue that the magnetic field of a newborn neutron star could have been early buried. during this phase, thermal neutrinos are created mainly by the pair annihilation, plasmon decay, photo-neutrino emission and other processes. we study the dynamics of these neutrinos in this environment and also estimate the number expected of the neutrino events with their flavor ratios on earth. the neutrino burst is the only viable observable that could provide compelling evidence of the hypercritical phase and therefore, the hidden magnetic field mechanism as the most favorable scenario to explain the anomalous low magnetic fields estimated for ccos. | hypercritical accretion scenario in central compact objects accompanied with an expected neutrino burst |
intensity interferometry is a technique that has been used to measure the size of sources ranging from the quark-gluon plasma formed in heavy ion collisions to the radii of stars. we investigate using the same technique to measure protoneutron star (pns) radii with the neutrino signal received from a core-collapse supernovae. using a full wave-packet analysis, including the neutrino mass for the first time, we derive criteria where the effect can be expected to provide the desired signal, and find that neutrinos from the next galactic supernova should contain extractable pns radius information. | neutrino intensity interferometry: measuring protoneutron star radii during core-collapse supernovae |
at the end of a massive star’s life, a violent explosion known as a supernova occurs and releases 99% of the star’s gravitational binding energy in the form of neutrinos. although the explosion generates a huge burst of neutrinos, the large distance to earthbound detectors, low cross sections, and flavour changing oscillations can make detection and analysis challenging. only one neutrino burst from a supernova has ever been detected, but neutrino detectors have been waiting patiently for another. the sno+ detector at snolab can be used as a supernova detector during both regular operation and calibrations by measuring the burst of neutrinos from a supernova. we present the neutrino detection method and analysis of potential galactic supernova with the sno+ detector. | supernovae and sno+ |
mup is the minimum stellar mass that, after the core-helium burning, develops temperature and density conditions for the occurrence of a hydrostatic carbon burning. stars whose mass is lower than this limit are the progenitors of c-o white dwarfs and, when belong to a close binary system, may give rise to explosive phenomena, such as novae or type ia supernovae. stars whose mass is only slightly larger than mup ignite c in a degenerate core and, in turn, experience a thermonuclear runaway. their final fate may be a massive o-ne wds or, if the core mass approaches the chandrasekhar limit, an e-capture sne. more massive objects ignite c in non-degenerate conditions. these “massive “ stars are the progenitors of various kind of core-collapse supernovae (type iip. iil, iin, ib, ic). it goes without saying that mup is a fundamental astrophysical parameter. from its knowledge depends our understanding of the sne progenitors, of their rates, of the chemical evolution, of the wd luminosity functions and much more. a precise evaluation of mup relies on our knowledge of various input physics used in stellar modeling, such as the plasma neutrino rate, responsible of the cooling of the core, the equation of state of high density plasma, which affects the heating of the contracting core and its compressibility, and some key nuclear reaction rates, such as, in particular, the 12c+12c and the 12c+α. in this paper we review the efforts made to determine this important parameter and we provide an up-to-date evaluation of the uncertainties due to the relevant nuclear physics inputs. | do we really know mup (i.e. the transition mass between type ia and core-collapse supernova progenitors)? |
understanding the mechanism of core-collapse supernova explosions requires knowledge of the nuclear equation of state (eos). recent multi-dimensional numerical simulations indicate that explosions are possible. nevertheless, it is not yet fully understood which equation of state is realized in the proto-neutron star formed during sn explosions. we examine the eos sensitivity of the relic supernova neutrino spectrum as a probe of the nuclear eos. this sensitivity arises largely from the contribution to neutrino emission from failed supernovae. we consider a variety of astrophysical scenarios, which include different progenitor masses for a successful explosion, the cosmological star formation rate, starbursts, quiescent star formation, and the metallicity dependence of the initial mass function. we find that the eos signature remains robust under a variety of conditions. we demonstrate the viability of future neutrino detectors to distinguish the nuclear eos via the relic supernova neutrino spectrum. | eos dependence of the relic supernova neutrino spectrum |
understanding neutrino flavor transformation in dense environments such as core-collapse supernovae (ccsn) is critical for inferring the physics of these events and interpreting a detected neutrino signal. the role of direction-changing collisions in shaping the neutrino flavor field in these environments is important and poorly understood; it has not been treated self-consistently. there has been progress, via numerical integration, to include the effects of collisions in the dynamics of the neutrino flavor field. while this has led to important insights, integration is limited by its requirement that full initial conditions must be assumed known. on the contrary, it has been shown in recent years that feedback from collisions to the field is a boundary value problem. numerical integration techniques are poorly equipped to handle that formulation. this paper demonstrates that an inference formulation of the problem can solve a simple collisions-only model representing a ccsn core-without full knowledge of initial conditions. specifically, the procedure solves a two-point boundary value problem with partial information at the bounds. the model is sufficiently simple that physical reasoning may be used as a confidence check on the inference-based solution, and the procedure recovers the expected model dynamics. this result demonstrates that inference can solve a problem that is artificially hidden from integration techniques—-a problem that is an important feature of flavor evolution in dense environments. thus, it is worthwhile to explore means of augmenting the existing powerful integration tools with inference-based approaches. | inference solves a boundary-value collision problem with relevance to neutrino flavor transformation |
sterile neutrinos of kev masses are one of the most promising candidates for the warm dark matter, which could solve the small-scale problems encountered in the scenario of cold dark matter. we present a detailed study of the production of such sterile neutrinos in a supernova core, and derive stringent bounds on the active-sterile neutrino mixing angles and sterile neutrino masses based on the standard energy-loss argument. | supernova bounds on kev-mass sterile neutrinos |
in this article the role of the supersaturation density equation of state (eos) is explored in simulations of failed core-collapse supernova explosions. therefore the nuclear eos is extended via a one-parameter excluded-volume description for baryons, taking into account their finite and increasing volume with increasing density in excess of saturation density. parameters are selected such that the resulting supernova eos represent extreme cases, with high pressure variations at supersaturation density which feature extreme stiff and soft eos variants of the reference case, i.e. without excluded-volume corrections. unlike in the interior of neutron stars with central densities in excess of several times saturation density, central densities of core-collapse supernovae reach only slightly above saturation density. hence, the impact of the supersaturation density eos on the supernova dynamics as well as the neutrino signal is found to be negligible. it is mainly determined from the low- and intermediate-density domain, which is left unmodified within this generalized excluded volume approach. | constraining the supersaturation density equation of state from core-collapse supernova simulations?. excluded volume extension of the baryons |
this paper describes algorithms for nonrelativistic hydrodynamics in the toolkit for high-order neutrino radiation hydrodynamics (thornado), which is being developed for multiphysics simulations of core-collapse supernovae (ccsne) and related problems with runge-kutta discontinuous galerkin (rkdg) methods. more specifically, thornado employs a spectral-type nodal collocation approximation, and we have extended limiters—a slope limiter to prevent nonphysical oscillations and a bound-enforcing limiter to prevent nonphysical states—from the standard rkdg framework to be able to accommodate a tabulated nuclear equation of state (eos). to demonstrate the efficacy of the algorithms with a nuclear eos, we first present numerical results from basic test problems in idealized settings in one and two spatial dimensions, employing cartesian, spherical-polar, and cylindrical coordinates. then, we apply the rkdg method to the problem of adiabatic collapse, shock formation, and shock propagation in spherical symmetry, initiated with a 15 m⊙ progenitor. we find that the extended limiters improve the fidelity and robustness of the rkdg method in idealized settings. the bound-enforcing limiter improves the robustness of the rkdg method in the adiabatic collapse application, while we find that slope limiting in characteristic fields is vulnerable to structures in the eos—more specifically, in the phase transition from nuclei and nucleons to bulk nuclear matter. the success of these applications marks an important step toward applying rkdg methods to more realistic ccsn simulations with thornado in the future. * this manuscript has been authored in part by ut-battelle, llc, under contract de-ac05-00or22725 with the us department of energy (doe). the us government retains and the publisher, by accepting the article for publication, acknowledges that the us government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for us government purposes. doe will provide public access to these results of federally sponsored research in accordance with the doe public access plan (http://energy.gov/downloads/doe-public-access-plan). | thornado-hydro: a discontinuous galerkin method for supernova hydrodynamics with nuclear equations of state |
most of the energy released by the gravitational collapse of the cores of massive stars is carried away by neutrinos. the self-consistent problem of gravitational collapse is solved using 2d gas dynamics considering the spectral transport of neutrinos in the flux-limited diffusion. it is shown that large-scale convection develops in the region near the neutrinosphere and leads to an increase in the average neutrino energy up to 15-18 mev, which is 1.5 times higher than the results of 1d calculations. this study improves a simple model of neutronization in the central opaque region, which is applicable, strictly speaking, only in the transparent region. the 2d model correctly reproduces the high chemical potential of degenerate electrons ~60 mev at the center with a high density of matter, as in spherically symmetric calculations with exact account of the weak interaction. since neutronization at the center is reversible due to trapped neutrinos, the instability development in the center is suppressed, and the high chemical potential of electrons at the center in the refined neutronization model does not affect the energy of outgoing neutrinos. the obtained neutrino energies are important both for explaining the supernova phenomenon and for setting up an experiment to detect neutrinos from a supernova. | nonequilibrium neutronization and large-scale convection in gravitational collapse |
low-energy neutrinos are clean messengers from supernovae explosions and probably carry unique insights into the process of stellar evolution. we estimate the expected number of events considering coherent elastic scattering of neutrinos off silicon nuclei, as would happen in charge coupled devices (ccd) detectors. the number of expected events, integrated over a window of about 18 s, is ∼ 4 if we assume 10 kg of silicon and a supernovae 1 kpc away. for a distance similar to the red supergiant betelgeuse, the number of expected events increases to ∼ 30-120, depending on the supernovae model. we argue that silicon detectors can be effective for supernovae neutrinos, and might possibly distinguish between models for certain target masses and distances. | supernovae neutrino detection via coherent scattering off silicon nuclei |
the neutrino beam driven instability of fast and slow magnetosonic waves with oblique applied magnetic field in multi-component ion, electron and neutrino beam plasma is studied. the dissipation effects of ion-neutral collisions are also included in the model. the neutrino and electron interactions through electro-weak force are included. it is found that the dissipation of ion collisions has significant effect on the phase velocity of the wave propagation and growth rate of the neutrino beam driven instability. the analytical expression of the growth rate of the fast and slow magnetosonic waves instability is found under the weak neutrino beam approximation and in the absence of ions and neutrals (atoms) collision effect. the numerical illustration of growth rates of the fast and slow magnetosonic waves are also presented with variations of magnetic field angle, neutrino beam energy, neutrino beam density, magnetic field intensity. it is found that the growth rate of the fast magnetosonic wave is maximum in case of the perpendicular directed magnetic field to the direction of wave propagation, while growth rate of slow magnetosonic wave is minimum in that case. it is also noticed that growth rate of fast magnetosonic wave comes out to be larger (of the order tens) than the slow magnetosonic wave case, which is quite different from earlier published results of type ii core-collapse supernova. | neutrino beam driven instability of magnetosonic waves in the presence of oblique magnetic field and ion-neutral collisional effect in plasmas |
the cryogenic apparatus for precision tests of argon interactions with neutrinos (captain) program is designed to make measurements of scientific importance to long-baseline neutrino physics and physics topics that will be explored by large underground detectors. the experiment employs two liquid argon time projection chambers (lartpcs), a primary detector with a mass of approximately 10 ton that will be deployed at different facilities for physics measurements and a two ton prototype detector for configuration testing. the physics programs for captain include measuring neutron interactions at the los alamos neutron science center, measuring neutrino interactions in the high-energy regime (1.5-5 gev) at fermilab numi beam, and measuring neutrino interactions in the low-energy regime (<50 mev) at stopped pion sources for supernova neutrino studies. the prototype detector (mini-captain) has been commissioned and the first uv laser track has been seen in its tpc. this paper gives an overview of the captain program and reports the status of the commissioning. the up-to-date detector design and running plans are also described. | the captain experiment |
the large volume detector (lvd) at infn laboratori nazionali del gran sasso, italy is a 1 kt liquid scintillator neutrino observatory mainly designed to study low energy neutrinos from gravitational stellar collapses (gsc) with 100% efficiency over the entire galaxy. here we summarize the results of the search for supernova neutrino bursts over the full data set lasting from june 1992 to may 2016 for a total live time of 8211 days. in the lack of a positive observation, either in standalone mode or in coincidence with other experiments, we establish the upper limit to the rate of gsc event in the milky way: 0.1 year-1 at 90% c.l.. | the core collapse supernova rate from 24 years of data of the large volume detector |
the conventional neutrino transport theory for core-collapse supernovae misses one key property of neutrinos: the left-handedness. the chirality of neutrinos modifies the hydrodynamic behavior at the macroscopic scale and leads to topological transport phenomena. we argue that such transport phenomena should play important roles in the evolution of core-collapse supernovae, and, in particular, lead to a tendency toward the inverse energy cascade from small to larger scales, which may be relevant to the origin of the supernova explosion. | chiral transport of neutrinos in supernovae |
this paper presents the scenario that gravitational waves, generated in core-collapse of a pre-supernova star, can produce both electromagnetic radiation and sound radiation as the gravitational wave propagates outward from the collapsing core. while the energy of this co-produced electromagnetic and/or sound radiation is orders of magnitude smaller than the initiating gravitational radiation, the electromagnetic/sonic power may be sufficient to re-ignite fusion outside the collapsing core. the non-equilibrium re-ignition of fusion, in roughly the same time frame as the strongest neutrino emissions, would change the configuration of the pre-supernova star. although the co-produced electromagnetic/sonic radiation is not powerful enough to contribute directly to the supernova, the associated non-equilibrium re-ignition of fusion could alter the state outside the core. the aim of this paper is to argue that the effect of this hypothesized co-produced electromagnetic/sonic radiation should be included in computational models of core collapse supernovae. | production of electromagnetic and sound radiation from gravitational waves in core-collapse supernovae |
neutrino interactions in low energy regions below 30 mev, where the experimental searches for supernova relic neutrino are conducted, have a large uncertainty due to complicated nuclear effects such as the pauli blocking effect and de-excitation of a residual nucleus. understanding the effect of nuclear de-excitation is especially critical since neutrons measured by liquid scintillator detectors can be emitted via de-excitation. we build a systematic method to predict nuclear de-excitation associated with neutrino-carbon interaction using talys and geant4. this prediction is combined with the results of neutrino event generators, and we find a large increase in neutron multiplicity. | nuclear de-excitation associated with neutrino-carbon interactions |
assessing the consistency of parameter constraints derived from different cosmological probes is an important way to test the validity of the underlying cosmological model. in an earlier work [1], we computed constraints on cosmological parameters for λcdm from an integrated analysis of cmb temperature anisotropies and cmb lensing from planck, galaxy clustering and weak lensing from sdss, weak lensing from des sv as well as type ia supernovae and hubble parameter measurements. in this work, we extend this analysis and quantify the concordance between the derived constraints and those derived by the planck collaboration as well as wmap9, spt and act. as a measure for consistency, we use the surprise statistic [2], which is based on the relative entropy. in the framework of a flat λcdm cosmological model, we find all data sets to be consistent with one another at a level of less than 1σ. we highlight that the relative entropy is sensitive to inconsistencies in the models that are used in different parts of the analysis. in particular, inconsistent assumptions for the neutrino mass break its invariance on the parameter choice. when consistent model assumptions are used, the data sets considered in this work all agree with each other and λcdm, without evidence for tensions. | integrated cosmological probes: concordance quantified |
the spin light of neutrino (slν) is a new possible mechanism of electromagnetic radiation by a massive neutrino (with a nonzero magnetic moment) moving in media. since the prediction of this mechanism, the question has been debated in a number of publications as whether the effect can be of any significance for realistic astrophysical conditions. although this effect is strongly suppressed due to smallness of neutrino magnetic moment, for ultra-high energy neutrinos (pev neutrinos recently observed by the icecube collaboration, for instance) the slν might be of interest in the case of neutrinos propagating in dense matter. an advanced view on the slν in matter is given, and several astrophysical settings (a neutron star, supernova, gamma-ray burst (grb), and relic neutrino background) for which the effect can be realized are considered. taking into account the threshold condition and also several competing processes, we determine conditions for which the slν mechanism is possible. we conclude that the most favorable case of the effect manifestation is provided by ultra dense matter of neutron stars and ultrahigh energy of the radiating neutrino, and note that these conditions can be met within galaxy clusters. it is also shown that due to the slν specific polarization properties this electromagnetic mechanism is of interest in the connection with the observed polarization of grb emission. | spin light of neutrino in astrophysical environments |
we present the results of a search for astrophysical sources of brief transient neutrino emission using icecube and deepcore data acquired between 2012 may 15 and 2013 april 30. while the search methods employed in this analysis are similar to those used in previous icecube point source searches, the data set being examined consists of a sample of predominantly sub-tev muon-neutrinos from the northern sky (-5° < δ < 90°) obtained through a novel event selection method. this search represents a first attempt by icecube to identify astrophysical neutrino sources in this relatively unexplored energy range. the reconstructed direction and time of arrival of neutrino events are used to search for any significant self-correlation in the data set. the data revealed no significant source of transient neutrino emission. this result has been used to construct limits at timescales ranging from roughly 1 s to 10 days for generic soft-spectra transients. we also present limits on a specific model of neutrino emission from soft jets in core-collapse supernovae. | the search for transient astrophysical neutrino emission with icecube-deepcore |
the theory and phenomenology of supernova neutrinos is reviewed, with focus on the most recent advancements on the neutrino flux predicted by supernova numerical models, on neutrino oscillations inside the star and in the earth, and on the physics of the diffuse supernova neutrino background. future directions of research are briefly summarized. | theory and phenomenology of supernova neutrinos |
the icecube neutrino observatory, which instruments 1$\,$km$^3$ of clear ice at the geographic south pole, was mainly designed to detect particles with energies in the multi-gev to pev range. due to ice temperatures between $-20^\circ$c to $-43^\circ$c and the low radioactivity of the ice, the dark noise rates of the 5160 photomultiplier tubes forming the icecube lattice are of order 500 hz, which is particularly low for 10 inch photomultipliers. therefore, icecube can extend its searches to bursts of $\mathcal{o}$(10$\,$mev) neutrinos lasting several seconds, which are expected to be produced by galactic core collapse supernovae. by observing a uniform rise in all photomultiplier rates, icecube can provide a particularly high statistical precision for the neutrino rate from supernovae in the inner part of our galaxy ($<$ 20 kpc). in this paper, the tools and the method to study potential obscured or failed core collapse supernovae in our galaxy are presented. the analysis will be based on 3911 days of icecube data taken between april 17, 2008 and december 31, 2018. | eleven year search for supernovae with the icecube neutrino observatory |
neutrinos from supernova (sn) bursts can give rise to detectable number of nuclear recoil (nr) events through the coherent elastic neutrino-nucleus scattering (ce$\nu$ns) process in large scale liquid xenon detectors designed for direct dark matter search, depending on the sn progenitor mass and distance. here we show that in addition to the direct nr events due to ce$\nu$ns process, the sn neutrinos can give rise to additional nuclear recoils due to the elastic scattering of neutrons produced through inelastic interaction of the neutrinos with the xenon nuclei. we find that the contribution of the supernova neutrino-induced neutrons ($\nu$i$n$) can significantly modify the total xenon nr spectrum at large recoil energies compared to that expected from the ce$\nu$ns process alone. moreover, for recoil energies $\gtrsim20$ kev, dominant contribution is obtained from the ($\nu$i$n$) events. we numerically calculate the observable s1 and s2 signals due to both ce$\nu$ns and $\nu$i$n$ processes for a typical liquid xenon based detector, accounting for the multiple scattering effects of the neutrons in the case of $\nu$i$n$, and find that sufficiently large signal events, those with s1$\gtrsim$50 photo-electrons (pe) and s2$\gtrsim$2300 pe, come mainly from the $\nu$i$n$ scatterings. | simulation of nuclear recoils due to supernova neutrino-induced neutrons in liquid xenon detectors |
the toolkit for high-order neutrino-radiation hydrodynamics (thornado) is being developed for simulations of core-collapse supernovae (ccsne) and related problems. current capabilities in thornado include solvers for the euler equations — in non-relativistic and special relativistic limits — and the two-moment model of neutrino transport. the spatial discretization in thornado is based on the discontinuous galerkin (dg) method, which is receiving increased attention from the computational astrophysics community. in this paper, we provide an overview of the numerical methods for the euler equations in thornado, and present some encouraging preliminary numerical results from a set of basic tests in one and two spatial dimensions. this manuscript has been authored by ut-battelle, llc under contract no. de-ac05-00or22725 with the u.s. department of energy. the united states government retains and the publisher, by accepting the article for publication, acknowledges that the united states government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for united states government purposes. the department of energy will provide public access to these results of federally sponsored research in accordance with the doe public access plan (http://energy.gov/downloads/doe-public-access-plan). | thornado-hydro: towards discontinuous galerkin methods for supernova hydrodynamics |
the properties of massive protoneutron stars (pnss) are of great significance for the study of supernova and the evolution of neutron stars or black holes. the mass of the massive neutron star psr j1614-2230 is fitted by selecting the nuclear coupling constants and adjusting the hyperon coupling constants in the framework of the relativistic mean field (rmf) theory. the model is then extrapolated to calculate the properties of massive pns with the trapped neutrinos. the effects of different trapped neutrinos on the composition and structure of massive pnss are discussed for entropy per baryon s = 1. results show that the presence of trapped neutrinos increase the energy density. moreover, the significant neutrinos trapped, such as electron leptons number yl = 0.4, reduces the pressure of massive pnss in the density region 0.2-0.5fm-3, that is to say, the equation-of-state (eos) is softened in this region. the maximum masses and corresponding radii of massive pnss are calculated to be 2.110m⊙, 2.106m⊙, 2.095m⊙, 2.082m⊙ and 12.19, 11.88, 11.75 and 11.81 km for the electron leptons number yl = 0.1, 0.2, 0.3, 0.4. we calculate the distribution of the internal temperature, and get the effects of the trapped neutrinos on the internal temperature of massive pnss for the first time. for the different electron leptons number yl = 0.1, 0.2, 0.3, 0.4, the central temperatures of the massive pns, when the mass is taken to be the same as that of the observed neutron star psr j1614-2230(1.97 ± 0.04m⊙), are 19.57-0.19+0.32, 22.55-0.25+0.36, 25.48-0.45+0.68, 27.47-0.83+0.93mev, respectively. | effects of trapped neutrinos on the composition and structure of massive protoneutron stars |
we calculate the stellar energy loss due to neutrino-pair production in e+e- annihilation in the context of a 331 model, a left-right symmetric model and a simplest little higgs model in a way that can be used in supernova calculations. we also present some simple estimates which show that such process can act as an efficient energy loss mechanism in the shocked supernova core. we find that the stellar energy loss is almost independent of the parameters of the models in the allowed range for these parameters. this work complements other studies on the stellar energy loss rate in e+e- annihilation. | stellar energy loss rates in the pair-annihilation process beyond the standard model |
most of the energy released in the gravitational collapse of the cores of massive stars is carried away by neutrinos. neutrinos play a pivotal role in explaining core-collape supernovae. currently, mathematical models of the gravitational collapse are based on multi-dimensional gas dynamics and thermonuclear reactions, while neutrino transport is considered in a simplified way. multidimensional gas dynamics is used with neutrino transport in the flux-limited diffusion approximation to study the role of multi-dimensional effects. the possibility of large-scale convection is discussed, which is interesting both for explaining sn ii and for setting up observations to register possible high-energy (≳10mev) neutrinos from the supernova. a new multi-dimensional, multi-temperature gas dynamics method with neutrino transport is presented. | large-scale instability during gravitational collapse with neutrino transport and a core-collapse supernova |
many galactic sources of gamma rays, such as supernova remnants, are expected to produce neutrinos with a typical energy cutoff well below 100 tev. for the icecube neutrino observatory located at the south pole, the southern sky, containing the inner part of the galactic plane and the galactic center, is a particularly challenging region at these energies, because of the large background of atmospheric muons. in this paper, we present recent advancements in data selection strategies for track-like muon neutrino events with energies below 100 tev from the southern sky. the strategies utilize the outer detector regions as veto and features of the signal pattern to reduce the background of atmospheric muons to a level which, for the first time, allows icecube searching for point-like sources of neutrinos in the southern sky at energies between 100 gev and several tev in the muon neutrino charged current channel. no significant clustering of neutrinos above background expectation was observed in four years of data recorded with the completed icecube detector. upper limits on the neutrino flux for a number of spectral hypotheses are reported for a list of astrophysical objects in the southern hemisphere. | neutrinos below 100 tev from the southern sky employing refined veto techniques to icecube data |
most of the energy released in the gravitational collapse of the cores of massive stars is carried away by neutrinos. neutrinos play a pivotal role in explaining core-collapse supernovae. in this work the multidimensional gas dynamics is used with neutrino transport in the flux-limited diffusion approximation to study the role of multi-dimensional effects. the possibility of large-scale convection is discussed, which is interesting both for explaining snii and for setting up observations to register possible high-energy (≲10 mev) neutrinos from the supernova. in compare with the previous work describing a new multidimensional gas dynamics method with neutrino transport we investigate the role of the rotation in the convection. | supernova explosion mechanism with the neutrinos and the collapse of the rotation core |
the effect of a magnetic field of arbitrary strength on the beta decay and crossing symmetric processes is analyzed. a covariant calculation technique is used to derive the expression for the squares of s-matrix elements of these reactions, which is also valid in reference frames in which the medium moves as a single whole along magnetic field lines. simple analytic expressions obtained for the neutrino and antineutrino emissivities for a moderately degenerate plasma fully characterize the emissivity and absorbability of the studied medium. it is shown that the approximation used here is valid for core collapse supernovae and accretion disks around black holes; beta processes in these objects are predominantly neutrino reactions. the analytic expressions obtained for the emissivities can serve as a good approximation for describing the interaction of electron neutrinos and antineutrinos with the medium of the objects in question and hold for an arbitrary magnetic field strength. due to their simplicity, these expressions can be included in the magnetohydrodynamic simulation of supernovae and accretion disks to calculate neutrino and antineutrino transport in them. the rates of beta processes and the energy and momentum emitted in them are calculated for an optically transparent matter. it is shown that the macroscopic momentum transferred in the medium increases linearly with the magnetic field strength and can substantially affect the dynamics of supernovae and accretion disks in the regions of a degenerate matter. it is also shown that the rates of beta processes and the energy emission for a magnetic field strength of b ≲ 1015 g typical of supernovae and accretion disks are lower than in the absence of field. this suppression is stronger for reactions with neutrinos. | effect of magnetic field on beta processes in a relativistic moderately degenerate plasma |
the research on supernovae explosions is one of the most exciting fields in astrophysics. recent studies show that the electron capture and beta decay play key roles in supernovae explosions. in this paper, the half-lives of some iron group nuclei by β--decay are investigated due to shell effect, pair effect, and the changes of the decay energy. we also discuss the influence of strong electron screening (ses) on the electron energy, beta decay threshold energy, and the antineutrino energy loss rates (aelr) in β- decay. the aelr increases, and the screening enhancement factor can get to 4.684 in ses due to q-value correction, shell and pairing effect. the aelr can be suppressed at lower density and higher temperature environment (e.g., 0.1 < ρ7 < 800, t9 > 30). the screening enhancement factor decreases about 14.10% (e.g., for 56ni). | an estimate of the antineutrino energy loss by beta decay on strongly screening iron group nuclei in presupernova |
after considering supernova shock effects, mikheyev-smirnov-wolfenstein effects, neutrino collective effects, and earth matter effects, the detection of supernova neutrinos at the china spallation neutron source is studied and the expected numbers of different flavor supernova neutrinos observed through various reaction channels are calculated with the neutrino energy spectra described by the fermi-dirac distribution and the “beta fit” distribution respectively. furthermore, the numerical calculation method of supernova neutrino detection on earth is applied to some other spallation neutron sources, and the total expected numbers of supernova neutrinos observed through different reactions channels are given. supported by national natural science foundation of china (11205185, 11175020, 11275025, 11575023) | detection of supernova neutrinos at spallation neutron sources |
aims: this paper proposes a new approach to detecting 𝒪(mev) neutrino bursts such as those associated with supernovae.methods: a novel `real-time test statistic' (rts) exploits the temporal structure of the expected signal, discriminating against the diffuse background, to allow detection of very weak signals that would elude standard clustering methods.results: for a given background rate, the proposed method increases signal efficiency while keeping the same false alarm rate for a poisson-distributed background. by adding a spatial penalty term to the definition of rts, it is also possible to reject spatially correlated backgrounds such as those due to spallation events.conclusions: the algorithm can be implemented in a real-time monitoring system for detectors of all sizes, allowing prompt alerts to be sent to the wider community, for example through the snews 2.0 network. | identification of neutrino bursts associated to supernovae with real-time test statistic (rts2) method |
core-collapse supernovae produce copious low-energy neutrinos and are also predicted to radiate gravitational waves. these two messengers can give us information regarding the explosion mechanism. the gravitational wave detection from these events are still elusive even with the already advanced detectors. here we give a concise and timely introduction to a new method that combines triggers from gw and neutrino observatories; more details shall be given in a forthcoming paper [1]. keywords: multimessenger, supernova, core-collapse, low-energy neutrino, gravitational wave. | joint analysis method on gravitational waves and low-energy neutrinos to detect core-collapse supernovae |
the destabilizing role of neutrino beams on the trivelpiece-gould modes is considered, assuming electrostatic perturbations in a magnetized plasma composed by electrons in a neutralizing ionic background, coupled to a neutrino species by means of an effective neutrino force arising from the electroweak interaction. the magnetic field is found to significantly improve the linear instability growth rate, as calculated for supernova type ii environments. on the formal level, for wave vectors parallel or perpendicular to the magnetic field, the instability growth rate is found from the unmagnetized case replacing the plasma frequency by the appropriated trivelpiece-gould frequency. the growth rate associated with oblique propagation is also obtained. | neutrino-driven electrostatic instabilities in a magnetized plasma |
we report preliminary results on the detection of the γ-rays from giant resonances of 16o and 12c nuclei from the experiment carried out at research center for nuclear physics osaka university. these γ-rays can be used to detect the μ and τ type neutrinos and anti-neutrinos, emitted from a core-collapse supernova, through neutral current reactions with 16o and 12c by large-scale neutrino detectors. | measurement of γ-rays from giant resonances of 16o and 12c with application to supernova neutrino detection |
the detection of the diffuse supernova neutrino background (dsnb) for the very first time and its difficulty due to the large irreducible backgrounds originally motivated the idea of adding gadolinium (gd) into the ultra-pure water of super-kamiokande (sk). since the main mode to detect the dsnb is through inverse beta decay, these backgrounds could be greatly reduced if neutrons could be detected with high efficiency. today, this is not currently possible. adding gd was proposed by gadzooks! about 10 years ago and since then much research has been done towards achieving this goal. given the many advantages that adding gd means, the egads project was set in 2009 to evaluate the gadolinium's action on detector systems. soon we will be able to demonstrate that this technique is possible, feasible at reasonable costs and safe making possible the advantages of reducing backgrounds in several analyses at sk or in future experiments like hyper-kamiokande. | egads approaching gadzooks! |
gamow-teller transitions in isotopes of chromium play a consequential role in the presupernova evolution of massive stars. β-decay and electron capture rates on chromium isotopes significantly affect the time rate of change of lepton fraction (dot{ye}). fine-tuning of this parameter is one of the key for simulating a successful supernova explosion. the (anti)neutrinos produced as a result of electron capture and β-decay are transparent to stellar matter during presupernova phases. they carry away energy and this result in cooling the stellar core. in this paper we present the calculations of gamow-teller strength distributions and (anti)neutrino energy loss rates due to weak interactions on chromium isotopes of astrophysical importance. we compare our results with measured data and previous calculations wherever available. | gamow-teller strength distributions and neutrino energy loss rates due to chromium isotopes in stellar matter |
we study the effects produced by interactions among neutrinos upon extra-galactic neutrino-fluxes. we have assumed a separable type of pair interactions and performed a transformation to a quasi-particle mean field followed by a tamm-damcoff diagonalization. in doing so, we have adopted techniques originated in the quantum many-body problem, and adapted them to this specific case. the solutions of the associated eigenvalue problem provide us with energies and amplitudes which are then used to construct the neutrino response functions at finite density and temperature. the formalism is applied to the description of neutrinos produced in a sn environment. | neutrino-pair interactions in astrophysical systems |
in this work, we examine the possibility of using the diffuse supernova neutrino background (dsnb) to test the chaplygin gas (cg) models of the universe. with a typical supernova rate rsn(z) and supernova neutrino spectrum dn(eν) / deν , the dsnb flux spectrum n(eν) in three categories of cg models, the generalized cg (gcg), modified cg (mcg) and extended cg (ecg) models, are studied. it is found that generally the flux spectra take a form similar to a fermi-dirac distribution with a peak centered around 3.80-3.97 mev. the spectrum shape and peak positions are primarily determined by rsn(z) and dn(eν) / deν and only slightly affected by the cg models. however, the height of the spectra in each category of the cg models can vary dramatically for different models, with variances of 13.2%, 23.6% and 14.9% for gcg, mcg and ecg categories respectively. the averaged total flux in each category are also different, with the ecg model average 10.0% and 12.7% higher than that of the gcg and mcg models. these suggest that the dsnb flux spectrum height and total flux can be used to constrain the cg model parameters, and if the measured to a sub-10% accuracy, might be used to rule out some models. | constraining chaplygin models using diffuse supernova neutrino background |
a neutrino propagating through fluctuating matter can experience large amplitude transitions between its states. such transitions occur in supernovae and compact object mergers due to turbulent matter profiles and neutrino self-interactions. in this paper we study, both numerically and analytically, three-flavour neutrino transformation through fluctuating matter built from two and three fourier modes (fms). we find flavour transformation effects which cannot occur with just two flavours. for the case of two fms we observe the equivalent of ‘induced transparency’ from quantum optics whereby transitions between a given pair of states are suppressed due to the presence of a resonant mode between another pair. when we add a third fm we find a new effect whereby the third mode can manipulate the transition probabilities of the two mode case so as to force complete transparency or, alternatively, restore ‘opacity’ meaning the perturbative hamiltonian regains its ability to induce neutrino flavour transitions. in both applications we find analytic solutions are able to match the amplitude and wavenumber of the numerical results to within a few percent. we then consider a case of turbulence and show how the theory can be used to understand the very different response of a neutrino to what appears to be two, almost identical, instances of turbulence. | neutrino flavour evolution through fluctuating matter |
in dune, the event timing provided by the detection of the relatively prompt scintillation photons will improve spatial resolution in the drift direction of the time-projection chamber (tpc) and is especially useful for non-beam physics topics such as supernova neutrinos and nucleon decay. the baseline design for the first 10kt single phase tpc fits the photon detector system in the natural gap between the wire planes of adjacent tpc volumes. a prototype photon detector design utilizes wavelength-shifter coated plates to convert the vacuum ultraviolet scintillation light to the optical and commercially-produced wavelength-shifting light guides to trap some of this light and transport it to an array of silicon photomultipliers at the end. this system and the testing performed to characterize the system and determine the efficiency are discussed. | liquid argon scintillation detection utilizing wavelength-shifting plates and light guides |
in this talk, i first summarize our current knowledge about the fundamental properties of neutrinos and emphasize the remaining unsolved problems in neutrino physics. then, recent theoretical results on neutrino mass models are introduced. different approaches to understanding tiny neutrino masses, lepton flavor mixing and cp violation are presented. finally, i report briefly some new progress in the studies of astrophysical neutrinos, including kev sterile neutrinos, supernova neutrinos and ultrahigh-energy cosmic neutrinos. | theoretical results on neutrinos |
a neutrino propagating through fluctuating matter can experience large amplitude transitions between its states. such transitions occur in supernovae and compact object mergers due to turbulent matter profiles and neutrino self-interactions. in this paper we study, both numerically and analytically, three-flavour neutrino transformation through fluctuating matter built from two and three fourier modes. we find flavor transformation effects which cannot occur with just two flavours. for the case of two fourier modes we observe the equivalent of "induced transparency" from quantum optics whereby transitions between a given pair of states are suppressed due to the presence of a resonant mode between another pair. when we add a third fourier mode we find a new effect whereby the third mode can manipulate the transition probabilities of the two mode case so as to force complete transparency or, alternatively, restore "opacity" meaning the perturbative hamiltonian regains its ability to induce neutrino flavour transitions. in both applications we find analytic solutions are able to match the amplitude and wavenumber of the numerical results to within a few percent. we then consider a case of turbulence and show how the theory can be used to understand the very different response of a neutrino to what appears to be two, almost identical, instances of turbulence. | neutrino flavour evolution through fluctuating matter |
in this presentation i summarize the main detection channels for neutrinos from core-collapse supernovae, and describe current status of and future prospects for supernova-neutrino-sensitive detectors worldwide. | supernova neutrino detection |
we study the evolution of neutrinos in a background matter moving with a linear acceleration. the dirac equation for a massive neutrino electroweakly interacting with background fermions is obtained in a comoving frame where matter is at rest. we solve this dirac equation for ultrarelativistic neutrinos. the neutrino quantum states in matter moving with a linear acceleration are obtained. we demonstrate that the neutrino electroweak interaction with an accelerated matter leads to the vacuum instability which results in the neutrino-antineutrino pairs creation. we rederive the temperature of the unruh radiation and find the correction to the unruh effect due to the specific neutrino interaction with background fermions. as a possible application of the obtained results we discuss the neutrino pairs creation in a core collapsing supernova. the astrophysical upper limit on the neutrino masses is obtained. | unruh effect for neutrinos interacting with accelerated matter |
we investigate the impact of a presumed axion-like-particle (alp) emission in a core-collapse supernova explosion on neutrino luminosities and mean energies employing a relatively simple analytic description. we compute the nuclear bremsstrahlung and primakoff axion luminosities as functions of the protoneutron star (pns) parameters and discuss how the alp luminosities compete with the neutrino emission, modifying the total pns thermal energy dissipation. our results are publicly available in the python package artisans, which can be used to compute the neutrino and axion observables for different choices of parameters. | analytic approach to axion-like-particle emission in core-collapse supernovae |
a major challenge of particle physics is determining the neutrino mass ordering (mo). due to matter effects, the flavor content of the neutrino flux from a core-collapse supernova (ccsn) depends on the true neutrino mo resulting in markedly different energy and angle distributions for the measured lepton in water cherenkov neutrino detectors. in this article, those distributions are compared for eight different ccsn models and used to study how their differences affect the determination of the neutrino mass ordering. in all cases, the inferred neutrino mass ordering is found to be either correct or inconclusive, with no significant false positives. however, the substantial variation observed among model predictions emphasizes the criticality of ongoing research in ccsn modeling. | uncovering the neutrino mass ordering with the next galactic core-collapse supernova neutrino burst using water cherenkov detectors |
i present my minority view that the majority (or even all) of core collapse supernovae (ccsne) are driven by jets rather than by neutrinos, and that the majority of type ia supernovae (sn ia) reach their explosion via the core degenerate scenario. new simulations presented at the meeting did not achieve an explosion of ccsne. i critically examine other arguments that where presented in support of the neutrino-driven model, and present counter arguments that support the jet-driven explosion mechanism. the jets operate via a negative jet feedback mechanism (jfm). the negative feedback mechanism explains the explosion energy being several times the binding energy of the core in most ccsne. we do not know yet what mechanism explodes massive stars and we do not know yet what evolutionary route leads white dwarfs to explode as sn ia, and so we must be open to different ideas and critically examine old notions. | a minority view on the majority: a personal meeting summary on the explosion mechanism of supernovae |
the inclusive neutrino/antineutrino-induced charged and neutral current reaction cross-sections in 12c, 16o, 40ar, 56fe and 208pb in the energy region of supernova neutrinos/antineutrinos are studied. the calculations are performed in the local density approximation (lda) taking into account the effects due to pauli blocking, fermi motion and the renormalization of weak transition strengths in the nuclear medium. the effect of coulomb distortion of the lepton produced in the charged current reactions has also been included. the numerical results for the energy dependence of the cross-section σ(e) as well as the flux averaged cross-section and event rates for the charged lepton production in the case of some supernova neutrino/antineutrino fluxes recently discussed in the literature have been presented. we have also given the flux-averaged angular and energy distributions of the charged leptons corresponding to these fluxes. | neutrino-nucleus cross-sections at supernova neutrino energies |
core-collapse supernovae are vital as the birthplace of compact objects, where one expects various phases of the dense matter. the current status of supernova studies with the nuclear data for dense matter and neutrino reactions is overviewed with a focus on recent progress of the neutrino-radiation hydrodynamics in two- an three-dimensions and remaining mysteries. in addition to its importance for the explosion mechanism, the equation of state is also essential to predict the neutrino bursts, which can be used to probe deep inside the compact objects. it is valuable to discuss variations of the extreme conditions for hyperons and quarks in central objects during explosive phenomena by looking into the pattern of neutrino signals in relation with dynamics and dense matter. | supernovae and neutron stars: playgrounds of dense matter and neutrinos |
the self-consistent problem of gravitational collapse is solved using 2d gas dynamics with taking into account the neutrino transfer in the flux-limited diffusion approximation. neutrino are described by spectral energy density, and weak interaction includes a simplified physical model of neutrino interactions with nucleons. i investigate convection on the stage of the collapse and then in the center of the core, where the unstable entropy profile was probably formed. it is shown that convection has large scale. convection appears only in the semitransparent region near the neutrinosphere due to non-equilibrium nonreversible neutronization. convection increases the energy of emitted neutrino up to 15÷18 mev. the obtained neutrino spectrum is important for the registration of low-energy neutrinos from a supernova. | a multidimensional multicomponent gas dynamic with the neutrino transfer in gravitational collapse |
in this paper, we calculate cross sections for charged-current neutrino-nucleus processes occuring under presupernova conditions. to treat thermal effects we extend self-consistent skyrme-qrpa calculations to finite temperature by using the formalism of thermo field dynamics. the numerical results are presented for the sample nuclei, $^{56}$fe and $^{82}$ge | neutrino processes with hot nuclei in supernovae |
the next galactic core-collapse supernova will deliver a wealth of neutrinos which for the first time we are well-situated to measure. these explosions produce neutrinos with energies between 10 and 100 mev over a period of tens of seconds. galactic supernovae are relatively rare events, occurring with a frequency of just a few per century. it is therefore essential that all neutrino detectors capable of detecting these neutrinos are ready to trigger on this signal when it occurs. this poster describes a data-driven trigger which is designed to detect the neutrino signal from a galactic core-collapse supernova with the nova detectors. the trigger analyzes 5ms blocks of detector activity and applies background rejection algorithms to detect the signal time structure over the background. this background reduction is an essential part of the process, as the nova detectors are designed to detect neutrinos from fermilab's numi beam which have an average energy of 2gev--well above the average energy of supernova neutrinos. | observing the next galactic supernova with the nova detectors |
the current status of the asd (artemovsk scintillation detector) experiment aimed at search for a neutrino flux from gravitational collapses of stellar cores is presented. experimental data obtained for 40 years of operation of the detector situated in a salt mine at a depth of 570 mwe are processed. the results obtained by calculating the expected signal in the detector on the basis of two models of supernova explosion are described. no candidates for neutrino bursts from gravitational star collapses have been revealed: the limit on the frequency of gravitational collapses was found to be less than one event per 17.15 yr at a 90% confidence level ( f col < 0.058 yr-1). | forty years to the artemovsk scintillation detector for neutrinos |
neutrinos are key particles in core-collapse supernovae. traveling unimpeded through the stellar core, neutrinos can be direct probes of the still uncertain and fascinating supernova mechanism. intriguing recent developments on the role of neutrinos during the stellar collapse are reviewed, as well as our current understanding of the flavor conversions in the stellar envelope. the detection perspectives of the next burst will be also outlined. | supernova neutrinos: new challenges and future directions |
the fact that the spatial velocity of pulsars is generally higher than that of their progenitor stars has bothered astronomers for nearly 50 years. it has been extensively argued that the high pulsar velocity should be acquired during a natal kick process on a timescale of 100 ms-10 s in the supernova explosion, in which some asymmetrical dynamical mechanism plays a key role. however, a satisfactory picture generally is still lacking. in this study, it is argued that the neutrino rocket model can well account for the high speed as well as the long-term evolution behaviors of pulsars. the neutrinos are emitted from superfluid vortex neutrons through the neutrino cyclotron radiation mechanism. the unique characters of left-handed neutrinos and right-handed antineutrinos resulting from the nonconservation of parity in weak interactions play a major role in the spatial asymmetry. the continuous acceleration of pulsars can be naturally explained by this model, which yields a maximum velocity surpassing 1000 km s-1. the alignment between the spinning axis and the direction of motion observed for the crab pulsar (psr 0531) and the vela pulsar (psr 0833) can be well accounted for. the observed correlation between the spin-down rate and the period of long-period pulsars with p ≳ 0.5 s can also be satisfactorily explained. | neutrino rocket jet model: an explanation of high-velocity pulsars and their spin-down evolution |
we show that nonstandard neutrino self-interactions can lead to total flavor equipartition in a dense neutrino gas, such as those expected in core-collapse supernovae. in this first investigation of this phenomenon in the multiangle scenario, we demonstrate that such a flavor equipartition can occur on very short scales, and therefore very deep inside the newly formed proto-neutron star, with a possible significant impact on the physics of core-collapse supernovae. our findings imply that future galactic core-collapse supernovae can appreciably probe nonstandard neutrino self-interactions, for certain cases even when they are many orders of magnitude smaller than the standard model terms. | nonstandard neutrino self-interactions can cause neutrino flavor equipartition inside the supernova core |
online calibration of neutrino liquid scintillator detector at energies above 10 mev is very important for study of such rare process as supernova and for correct calculation of backgrounds if spectral properties is the focus of researches. the traditional procedure implies the usage of radioactive sources with well-known spectral properties but such approach is limited by available radioactive sources, upper possible energies (∼10-11 mev) and dangerous for ultra low background environment of modern detectors. the approach we propose is based on simulation of events with controllable uv double led pulser. the led's main wavelength fits the scintillator excitation wavelength. this technique allows to simulate physical events within the detector in very wide energy range from a few hundred kev to about 50 mev. additional studies like pile-up analysis can be performed due to double-leds scheme which generates two delayed signals with different adjustable amplitudes. the delay time is also adjustable parameter. | online calibration of neutrino liquid scintillator detectors above 10 mev |
tension in the hubble constant (h_0) is reaching the point of no return, with nearly a dozen re-analyses and semi-independent measurements confirming that the present rate of cosmic expansion is faster than expected given early universe observations and the lambdacdm model. the most precise values of h_0 measured using the local distance ladder are now discrepant at the 4.4-sigma level with those inferred from the early universe. the h_0 tension is by far the most convincing current evidence for physics beyond lambdacdm, and could indicate dynamical dark energy, self-interacting neutrinos, or a new relativistic particle, among other possibilities. only one component of the distance ladder still lacks sufficient independent verification: type ia supernova (sn ia) distances. it is imperative that we test this final rung of the ladder before declaring a discovery of new physics. we propose a new survey to obtain cepheid distances for five highly star-forming galaxies in the hubble flow to build a two-rung distance ladder without sne ia that will be able to measure h_0 with 3.2% uncertainty and, if the measurement agrees with current estimates, could verify h_0 tension at the 3-sigma confidence level. our sample galaxies are also sn ia hosts, allowing these observations to increase the precision of the baseline distance ladder method. unlike current approaches, this new avenue to refine h_0 is not limited by the low rate of sn ia in the local volume. this program will therefore open a new window to achieving the highest priority science goal identified by the hst and fundamental physics working group: the best possible measurement of h_0 in the remaining years of hst. | tension at the breaking point: uncovering new physics through a two-rung distance ladder measurement of the hubble constant |
many galactic sources of gamma rays, such as supernova remnants, are expected to produce neutrinos with a typical energy cutoff well below 100 tev. for the icecube neutrino observatory located at the south pole, the southern sky, containing the inner part of the galactic plane and the galactic center, is a particularly challenging region at these energies, because of the large background of atmospheric muons. in this paper, we present recent advancements in data selection strategies for track-like muon neutrino events with energies below 100 tev from the southern sky. the strategies utilize the outer detector regions as veto and features of the signal pattern to reduce the background of atmospheric muons to a level which, for the first time, allows icecube searching for point-like sources of neutrinos in the southern sky at energies between 100 gev and several tev in the muon neutrino charged current channel. no significant clustering of neutrinos above background expectation was observed in four years of data recorded with the completed icecube detector. upper limits on the neutrino flux for a number of spectral hypotheses are reported for a list of astrophysical objects in the southern hemisphere. | neutrinos below 100 tev from the southern sky employing refined veto techniques to icecube data |
neutrinos play a key role in core-collapse supernova explosions. carrying information from deep inside the stellar core, neutrinos are direct probes of the supernova mechanism. intriguing recent developments on the role of neutrinos in supernovae are reviewed, as well as our current understanding of the flavor conversions in the stellar envelope, and the detection perspectives of the next burst. | supernova neutrinos: theory |
a possible mechanism for the formation of heavy-mass elements in supernovae is the rapid neutron-capture-mechanism (r-process). it depends upon the electron-fraction ye, a quantity which is determined by beta-decay-rates. in this paper, we focus on the calculation of electroweak decay-rates in presence of massive neutrinos. the resulting expressions are then used to calculate nuclear reactions entering the rapid-neutron capture. we fix the astrophysical parameters to the case of a core-collapse supernova. the neutrino sector includes a mass scheme and mixing angles for active neutrinos, and also by including the mixing between active and sterile neutrinos. the results of the calculations show that the predicted abundances of heavy-mass nuclei are indeed affected by the neutrino mixing. | neutrino mixing in nuclear rapid neutron-capture processes |
we consider scenario of the dark matter consisting of two fractions, stable part being dominant and a smaller unstable fraction, which has decayed after the recombination epoch. it has been suggested in ref. [1] that the above scenario may alleviate tension between high-redshift (cmb anisotropy) and low-redshift (cepheid variables and sne ia, cluster counts) cosmological measurements. we derive constraints on the heavy relics branching to qbar q, e+e-, μ+μ-, τ+τ-, νebar nue, νμbar nuμ, w+w- and γγ in the above scenario by comparison of the secondary γ and ν fluxes produced by the process with recent diffuse γ and ν flux measurements and show that the model is excluded for dm masses larger than 600 gev if there is no decay of dm to invisible radiation. | dark matter component decaying after recombination: constraints from diffuse gamma-ray and neutrino flux measurements |
the role of asymptotic giant branch (agb) stars in chemical enrichment is significant for producing 12,13c, 14n, f, 25,26mg, 17o and slow neutron-capture process (s-process) elements. the contribution from super-agb stars is negligible in classical, one-zone chemical evolution models, but the mass ranges can be constrained through the contribution from electron-capture supernovae and possibly hybrid c+o+ne white dwarfs, if they explode as type iax supernovae. in addition to the recent s-process yields of agb stars, we include various sites for rapid neutron-capture processes (r-processes) in our chemodynamical simulations of a milky way type galaxy. we find that neither electron-capture supernovae or neutrino-driven winds are able to adequately produce heavy neutron-capture elements such as eu in quantities to match observations. both neutron-star mergers (nsms) and magneto-rotational supernovae (mrsne) are able to produce these elements in sufficient quantities. using the distribution in [eu/(fe, α)] - [fe/h], we predict that nsms alone are unable to explain the observed eu abundances, but may be able to together with mrsne. in order to discuss the role of long-lifetime sources such as nsms and agb stars at the early stages of galaxy formation, it is necessary to use a model that can treat inhomogeneous chemical enrichment, such as in our chemodynamical simulations. in our cosmological, chemodynamical simulations, we succeed in reproducing the observed n/o-o/h relations both for global properties of galaxies and for local inter-stellar medium within galaxies, without rotation of stars. we also predict the evolution of cno abundances of disk galaxies, from which it will be possible to constrain the star formation histories. | the role of agb stars in galactic and cosmic chemical enrichment |
core-collapse supernovae, failed supernovae and quark novae are expected to release an energy of few 1053 ergs through mev neutrinos and a network of detectors is operative to look online for these events. however, when the source distance increases and/or the average energy of emitted neutrinos decreases, the signal statistics drops and the identification of these low statistic astrophysical bursts could be challenging. in a standard search, neutrino detectors characterise the observed clusters of events with a parameter called multiplicity, i.e. the number of collected events in a fixed time-window. we discuss a new parameter called ξ (=multiplicity/duration of the cluster) in order to add the information on the temporal behaviour of the expected signal with respect to background. by adding this parameter to the multiplicity we optimise the search of astrophysical bursts and we increase their detection horizon. moreover, the use of the ξ can be easily implemented in an online system and can apply also to a network of detectors like snews. for these reasons this work is relevant in the multi-messengers era when fast alerts with high significance are mandatory. | expanding core-collapse supernova search horizon of neutrino detectors |
we trained deep neural networks (dnns) as a function of the neutrino energy density, flux, and the fluid velocity to reproduce the eddington tensor for neutrinos obtained in our first-principles core-collapse supernova simulation. although the moment method, which is one of the most popular approximations for neutrino transport, requires a closure relation, none of the analytical closure relations commonly employed in the literature capture all aspects of the neutrino angular distribution in momentum space. in this paper, we develop a closure relation by using dnns that take the neutrino energy density, flux, and the fluid velocity as the inputs and the eddington tensor as the output. we consider two kinds of dnns: a conventional dnn, named a component-wise neural network (cwnn), and a tensor-basis neural network (tbnn). we find that the diagonal component of the eddington tensor is better reproduced by the dnns than the m1 closure relation, especially for low to intermediate energies. for the off-diagonal component, the dnns agree better with the boltzmann solver than the m1 closure relation at large radii. in the comparison between the two dnns, the tbnn displays slightly better performance than the cwnn. with these new closure relations at hand, based on dnns that well reproduce the eddington tensor at much lower costs, we have opened up a new possibility for the moment method. | deep learning of the eddington tensor in core-collapse supernova simulation |
providing an early warning of supernova burst neutrinos is of importance in studying both supernova dynamics and neutrino physics. the daya bay reactor neutrino experiment, with a unique feature of multiple liquid scintillator detectors, is sensitive to the full energy spectrum of supernova burst electron-antineutrinos. by utilizing 8 antineutrino detectors (ads) in the three different experimental halls which are about 1 km's apart from each other, we obtain a powerful and prompt rejection of muon spallation background than single-detector experiments with the same target volume. a dedicated trigger system embedded in the data acquisition system has been installed to allow the detection of a coincidence of neutrino signals of all ads via an inverse beta-decay (ibd) within a 10-second window, thus providing a robust early warning of a supernova occurrence within the milky way. an 8-ad associated supernova trigger table has been established theoretically to tabulate the 8-ad event counts' coincidence vs. the trigger rate. as a result, a golden trigger threshold, i.e. with a false alarm rate < 1/3-months, can be set as low as 6 candidates among the 8 detectors, leading to a 100% detection probability for all 1987a type supernova bursts at the distance to the milky way center and a 96% detection probability to those at the edge of the milky way. | highlight on supernova early warning at daya bay |
the gadzooks! project pursues the upgrade of the super-kamiokande detector as a way to efficiently detect thermal neutrons. inverse beta decay reactions, as well as charged current quasi-elastic (ccqe) scattering of low energy anti-neutrinos (up to a few hundreds of mev) in sk, produce one positron and one neutron in the final state. being able to observe the final state neutron in coincidence with the prompt positron would mean that sk could identify these reactions as genuine with very high confidence. gadzooks! will open to super-kamiokande - and water cherenkov detectors in general - a wealth of physics currently inaccessible due to background limitations. the most important is observing for the first time the diffuse supernova neutrino background: super-kamiokande enriched with gadolinium will discover it after few years of running. the main r&d program towards gadzooks! is egads: a 200 ton fully instrumented tank built in a new cavern in the kamioka mine. egads incorporates all the necessary subsystems to make gadzooks! a reality. in this contribution we will describe egads, we will present its current status and discuss the main results and conclusions arrived at so far. in addition, we will analyze other issues specific to the running of gadzooks!. | status of gadzooks!: neutron tagging in super-kamiokande |
in this work we analyze the effects of quantum decoherence upon the precession of the neutrino polarization vector in a supernovae-like environment. in order to perform the study we have determined the time-dependence of the polarization vector by solving the equation of motion for different neutrino-mixing schemes. the results of the calculations show that the onset of decoherence depends strongly on the parameters of the adopted mixing scheme. as examples we have considered : a) the mixing between active neutrinos and b) the mixing between active end sterile neutrinos. | decoherence-effects in the neutrino-mixing mechanism: active and sterile neutrinos in the three flavor scheme |
the physical ingredients and processes ruling the violent death of a massive star are reviewed, from the collapse of its core to the birth of a neutron star and the ejection of the stellar envelope. the crucial phase of this transition results from the complex interplay of many fields of physics: quantum physics, gravitation, nuclear physics, neutrino physics, and magnetohydrodynamics. recent numerical simulations have revealed the diversity of explosion paths induced by the diversity of progenitor structures. 3d simulations are now capable of exploring the consequences of pre-collapse asymmetries in the stellar core, such as the distribution of angular momentum, magnetic fields, and combustion inhomogeneities. they also revealed the limitations of the 2d results which assumed an axisymmetric evolution. even with the fastest computers, physical approximations are still unavoidable to calculate neutrino transport. we describe the explosion physics based on the most robust results, privileging simplified descriptions conducive to the deepest physical understanding. we emphasize the role of hydrodynamical instabilities and their consequences on the nonspherical character of the explosion. | explosion physics of core-collapse supernovae |
we present an implementation of icecube in the snowglobes package, which is used to calculate expected detection event rates resulting from supernova neutrinos. the snowglobes package is widely used to compare the sensitivity of different neutrino observatories, but currently does not include simulation files for icecube. in this paper, we give a brief overview of the design process that went into this implementation. | implementing icecube in snowglobes |
neutrinos from supernova (sn) bursts can give rise to detectable number of nuclear recoil (nr) events through the coherent elastic neutrino-nucleus scattering (ceυns) process in large scale liquid xenon detectors designed for direct dark matter search, depending on the sn progenitor mass and distance. here we show that in addition to the direct nr events due to cevns process, the sn neutrinos can give rise to additional nuclear recoils due to the elastic scattering of neutrons produced through inelastic interaction of the neutrinos with the xenon nuclei. we find that the contribution of the supernova neutrino-induced neutrons (υin) can significantly modify the total xenon nr spectrum at large recoil energies compared to that expected from the ceυns process alone. moreover, for recoil energies ≳ 20 kev, dominant contribution is obtained from the (υin) events. we numerically calculate the observable s1 and s2 signals due to both cevns and vin processes for a typical liquid xenon based detector, accounting for the multiple scattering effects of the neutrons in the case of υin, and find that sufficiently large signal events, those with s1≳50 photo-electrons (pe) and s2≳2300 pe, come mainly from the υin scatterings. | simulation of nuclear recoils due to supernova neutrino-induced neutrons in liquid xenon detectors |
neutrinos in water can be detected thanks to several reactions. the most important one is the inverse beta decay bar nue + p → n + e+. the detection of 2.2 mev γ from neutron capture on free protons is very difficult. the feasibility of gadolinium (gd) doping in water cherenkov detectors essentially reduces background signals and enhances the sensitivity to neutrino detection. in this work the supernova neutrino charged-current interactions with the most abundant gd even isotopes (a=156,158 and 160) are studied. we use measured spectra and the quasiparticle random phase approximation to calculate the charged current response of gd isotopes to supernova neutrinos. flux-averaged cross sections are obtained considering quasi-thermal neutrino spectra. | supernova neutrino scattering off gadolinium even isotopes in water cherenkov detectors |
we study the effect of non-standard neutrino interactions (nsis) on the growth of instabilities in neutrino energy spectra of a core-collapse supernova for different neutrino intensities and/or types of nsis, notably including the exotic neutrino magnetic moment. although it is usually attested that instabilities virtually smear out all potentially observable signatures, we show that, instead, there are regimes in which they act as a magnifying glass, bringing tiny effects to the eye of the observer. | instabilities of collective neutrino oscillations induced by non-standard neutrino interactions |
weak interaction processes play an important role for the dynamics of a core-collapse supernova. due to progress of nuclear modeling and constrained by data it has been possible to improve the rates of these processes for supernova conditions decisively. this manuscript describes the recent advances and the current status in deriving electron capture rates on nuclei and of inelastic neutrino-nucleus scattering for applications in supernova simulations and briefly discusses their impact on such studies. | weak-interaction processes in core-collapse supernovae |
recent upgrades to the super-kamiokande neutrino observatory will allow it to trace the history of exploding stars. | gigantic japanese detector prepares to catch neutrinos from supernovae |
supernova neutrino bursts have been observed from extragalactic distances. this note addresses the question of how gravitational lensing could distort the information in the burst. we apply the gravitational lens hypothesis to try to understand the time and brightness structure of the sn1987a neutrino observations. estimates of a possible lensing mass and alignment are made. these estimates suggest a path to verification. | gravitational lensing of supernova neutrino bursts |
we present a methodical study of the thermal and nuclear properties for the hot nuclear matter using relativistic-mean field theory. we examine the effects of temperature on the binding energy, pressure, thermal index, symmetry energy, and its derivative for the symmetric nuclear matter using temperature-dependent relativistic mean-field formalism for the well-known g2⁎ and recently developed iopb-i parameter sets. the critical temperature for the liquid-gas phase transition in an asymmetric nuclear matter system has also been calculated and collated with the experimentally available data. we investigate the approach of the thermal index as a function of nucleon density in the wake of relativistic and non-relativistic formalism. the computation of neutrino emissivity through the direct urca process for the supernovae remnants has also been performed, which manifests some exciting results about the thermal stabilization and evolution of the newly born proto-neutron star. the central temperature and the maximum mass of the proto-neutron star have also been calculated for different entropy values. | thermal impacts on the properties of nuclear matter and young neutron star |
the tokai intermediate tank with unoscillated spectrum (titus) detector is a proposed addition to the hyper-kamiokande (hk) experiment located approximately 2 km from the j-parc neutrino beam. the design consists of a 2 kton gadolinium (gd) doped water cherenkov detector, surrounded by a magnetized iron detector designed to range-out muons. the target material and location are chosen so that the neutrino interactions and beam spectrum at titus will match those of hk. including a 0.1% gd concentration allows for neutrino/antineutrino discrimination via neutron tagging. the primary goal of titus is to directly measure the neutrino flux and make cross-section measurements that reduce the systematic uncertainty of the long-baseline oscillation physics program at hk and enhance its sensitivity to cp violation. titus can also be used for physics unrelated to the j-parc beam, functioning as an independent detector for supernova neutrino bursts and measuring the neutron rate to improve hk proton decay searches. | titus: an intermediate distance detector for the hyper-kamiokande neutrino beam |
it has recently been demonstrated analytically that the two-point correlation function for pairs of neutrinos may contain information about the size of the protoneutron star formed in a galactic core-collapse supernova. the information about the size of the source emerges via the neutrino equivalent of intensity interferometry originally used by hanbury-brown and twiss with photons to measure the radii of stars. however the analytic demonstration of neutrino intensity interferometry with supernova neutrinos made a number of approximations: that the two neutrinos had equal energies, that the neutrinos were emitted at simultaneous times from two points and that they were detected simultaneously at two detection points that formed a plane with the emission points. these approximations need to be relaxed in order to better determine the feasibility of neutrino intensity interferometry for supernovae neutrinos in a more realistic scenario. in this paper we further investigate the feasibility of intensity interferometry for supernova neutrinos by relaxing all the approximations made in the earlier study. we find that, while relaxing any one assumption reduces the correlation signal, the relaxation of the assumption of equal times of detection is by far the largest detrimental factor. for neutrino energies of order ∼15 mev and a supernova distance of l =10 kpc , we show that in order to observe the interference pattern in the two-point correlation function of the neutrino pairs, the timing resolution of a detector needs to be on the order of ≲10-21 s if the initial neutrino wave packet has a size of σx∼10-11 cm . | feasibility of using neutrino intensity interferometry to measure protoneutron star radii |
most supernova theories state that this phenomenon lasts for a few seconds and ends with a big final explosion. however, these theories do not take into account several experimental results obtained with neutrino and gravitational wave detectors during the explosion of sn 1987a, the only supernova observed in a nearby galaxy in modern age. according to these experimental results the phenomenon is much more complex that envisaged by current theories, and has a duration of several hours. since recent data of the x-ray nasa satellite nustar show a clear evidence of an asymmetric collapse, we have revisited the experimental data recorded by some underground and gravitational wave detectors running at the time of sn 1987a. new evidence is shown that confirms the previous results, namely that the data recorded by the gravitational wave detectors running in rome and in maryland are strongly correlated with the data of both the lsd (mont blanc) and the kamiokande detectors, and that the correlation extends over a long period of time (one or two hours) centered at the mont blanc time. in addition, the signals of the gw detectors preceded the signals of the underground detectors by a time of order of one second. this result, obtained by comparing six independent files of data recorded by four different experiments located at intercontinental distances, indicates that also kamiokande detected neutrinos at themont blanc time, but these interactions were not identified because not grouped in a burst. a similar correlation was also found in the data of the underground experiments in mont blanc and baksan. | supernova 1987a, 30 years later |
supernova 1987a in the large magellanic cloud was the first naked-eye supernova since kepler's supernova in 1604. neutrino detections from the event dramatically confirmed the long-held belief that this type of supernova is triggered by the final collapse of the core of a massive star, but in many other respects it was a very unusual, even anomalous event. the progenitor was a blue supergiant instead of a red supergiant, as had been predicted theoretically, and the system was surrounded by a spectacular triple-ring nebula that consists of material that was ejected only 20,000 years before the explosion. this chapter will discuss the mystery of the supernova progenitor and how all the evidence points toward a dramatic event that occurred some 20,000 years ago, the merger of two massive stars and how future observations will further help to prove or refute the current picture. | the progenitor of sn 1987a |
registration of supernova neutrinos is one of the main goals of large underground neutrino detectors. we consider the possibility of using the large water veto tanks of future dark matter experiments as the additional facilities for supernova detection. simulations were performed for registration of cherenkov light in 2 kt water veto of darkside-20k from high energy positrons created by supernova electron antineutrinos via inverse beta decay reaction. comparison between characteristics of different supernova neutrino detectors are presented. | supernova registration in water cherenkov veto of dark matter detectors |
calculations using astrophysical equations of state at low densities comparable to that of the neutrino emission surface in supernovae and accretion disks are confronted with experimental results from heavy ion collisions. an extension of previous work shows that it is important to include all of the measured experimental data to draw conclusions about the astrophysical equation of state. armed with this information, the calculations of the astrophysical equation of state are significantly constrained. predictions of temperatures and densities sampled in black hole accretion disks are compared to those sampled in the experimental data. | from femtonova to supernova: heavy-ion collisions and the supernova equation of state |
the interaction of the flux of electron neutrinos arising owing to the effect of the rotationalcollapse mechanism at the first stage of supernova burst with lsd components, such as 56fe (a large amount of this metal is contained in lsd as a shielding material) and c n h2 n+2 liquid scintillator, is investigated. both charged and neutral channels of neutrino interaction with 12c and 56fe are considered. experimental data that make it possible to extract information necessary for calculating nuclear matrix elements appearing in the expression for the interaction cross section are used. the number of signals generated in lsd by the neutrino pulse from the supernova 1987a is determined. the results of this study are in good agreement with experimental data. | iron as a detector for neutrinos from collapsing stars |
recently, first neutrino-driven supernova explosions have been obtained in 3d, self-consistent, first-principle simulations, these models are still not always exploding robustly and, in general, the explosions are not sufficiently energetic. to constrain the explosion mechanism, and the related uncertainties, it is thus very helpful to consider observational constraints: pulsar kicks, progenitor association and supernova remnants (snr). recent observations of asymmetries in the supernova ejecta of cas a are very promising, to compare to long-term simulations of the explosion. in addition 3d observations of sn87a are becoming more constraining on the geometry of the ejected material during the explosion. in this talk i will discuss our efforts to model the late time evolution of a 3d supernova explosion, where we include the effects of beta decay, which inflates the structures rich in 56ni. the structures we find in the simulations depend on the quantities plotted. | the infancy of supernova remnants: evolving a supernova into its remnant in 3d |
in spite of its key role in compact star physics, the surface tension of quark matter is not well comprehended yet. in this work, we analyze the behavior of the surface tension of three flavor quark matter in the outer and inner core of cold deleptonized magnetars, proto magnetars born in core collapse supernovae, and hot magnetars produced in binary neutron stars mergers. we explore the role of temperature, baryon number density, trapped neutrinos, droplet size, and magnetic fields within the multiple reflection expansion formalism. quark matter is described within the mit bag model and is assumed to be in chemical equilibrium under weak interactions. we discuss some astrophysical consequences of our results. | the role of quark matter surface tension in magnetars |
we make projections for measuring the black hole birth rate from the diffuse supernova neutrino background (dsnb) by future neutrino experiments, and constrain the black hole merger fraction epsilon, when combined with information on the black hole merger rate from gravitational wave experiments such as ligo. the dsnb originates from neutrinos emitted by all the supernovae in the universe, and is expected to be made up of two components: neutrinos from neutron-star-forming supernovae, and a sub-dominant component at higher energies from black-hole-forming "unnovae". we perform a markov chain monte carlo analysis of simulated data of the dsnb in an experiment similar to hyper-kamiokande, focusing on this second component. since all knowledge of the neutrino emission from unnovae comes from simulations of collapsing stars, we choose two sets of priors: one where the unnovae are well-understood and one where their neutrino emission is poorly known. by combining the black hole birth rate from the dsnb with projected measurements of the black hole merger rate from ligo, we show that the fraction of black holes which lead to binary mergers observed today epsilon could be constrained to be within the range 2 ṡ 10-4 <= epsilon <= 3 ṡ 10-2 at 3 σ confidence, after ten years of running an experiment like hyper-kamiokande. | a "nu" look at gravitational waves: the black hole birth rate from neutrinos combined with the merger rate from ligo |
i review the state of investigation into the impact that nonspherical stellar progenitor structure has on the core-collapse supernova mechanism. although modeling stellar evolution relies on 1d spherically symmetric calculations, massive stars are not truly spherical. in the stellar evolution codes, this fact is accounted for by "fixes" such as mixing length theory and attendant modifications. of particular relevance to the supernova mechanism, the si- and o-burning shells surrounding the iron core at the point of collapse can be violently convective, with convective speeds of hundreds of km s-1. it has recently been shown by a number of groups that the presence of nonspherical perturbations in the layers surrounding the collapsing iron core can have a favorable impact on the likelihood for shock revival and explosion via the neutrino heating mechanism. this is due in large part to the strengthening of turbulence behind the stalled shock due to the presence of finite amplitude seed perturbations to speed the growth of convection which drives the post-shock turbulence. efforts are now underway to simulate the final minutes of stellar evolution to core-collapse in 3d with the aim to generate realistic multidimensional initial conditions for use in simulations of the supernova mechanism. | influence of non-spherical initial stellar structure on the core-collapse supernova mechanism |
a new neutrino magnetohydrodynamics (nmhd) model is formulated, where the effects of the charged weak current on the electron-ion magnetohydrodynamic fluid are taken into account. the model incorporates in a systematic way the role of the fermi neutrino weak force in magnetized plasmas. a fast neutrino-driven short wavelengths instability associated with the magnetosonic wave is derived. such an instability should play a central role in strongly magnetized plasma as occurs in supernovae, where dense neutrino beams also exist. in addition, in the case of nonlinear or high frequency waves, the neutrino coupling is shown to be responsible for breaking the frozen-in magnetic field lines condition even in infinite conductivity plasmas. simplified and ideal nmhd assumptions were adopted and analyzed in detail. | neutrino magnetohydrodynamics |
we report on the push method for artificially triggering core-collapse supernova explosions of massive stars in spherical symmetry. the push method increases the energy deposition in the gain region proportionally to the heavy flavor neutrino fluxes.we summarize the parameter dependence of the method and calibrate push to reproduce sn 1987a observables. we identify a best-fit progenitor and set of parameters that fit the explosion properties of sn 1987a, assuming 0.1 m⊙ of fallback. for the explored progenitor range of 18-21 m⊙, we find correlations between explosion properties and the compactness of the progenitor model. | pushing core-collapse simulations to explosion |
the properties of the neutron star crust are crucially important for many physical processes occurring in the star. for instance, the crustal transport coefficients define the temperature evolution of accreting stars after bursts, which can be compared to observation. furthermore, the structure of the inner crust can modify the neutrino transport through the matter considerably, significantly impacting the dynamics of supernova explosions. therefore, we perform numerical studies of the inner crust, and among other aspects, investigate the dependence of the pasta phase on the isospin properties of the nuclear interactions. to this end we developed an efficient computer code to simulate the inner and outer crust using molecular dynamics techniques. first results of the simulations and insights into the crust-core transition are presented. | simulations of the neutron star crust |
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