abstract stringlengths 3 192k | title stringlengths 4 857 |
|---|---|
the effects of the nuclear structure uncertainties on the description of processes induced by coherent scattering of neutrinos on nuclei are investigated. a reference calculation based on a specific nuclear model is defined and the cross sections and also the expected number of events produced by neutrinos generated by the explosion of a supernova in our galaxy, and by a spallation neutron source are evaluated. by changing the input parameters of the reference calculation their relevance on cross sections and on the number of the detected events is estimated. seven spherical nuclei with different proton to neutron ratios are considered as possible targets of the neutrinos in the detector, the lightest being 12c and the heaviest 208pb. the effects generated by the uncertainties of the nuclear model are much smaller than those due to the supernova neutrino flux models. this makes the coherent elastic neutrino-nucleus scattering a reliable tool to investigate the details of the neutrino sources, the neutrino-nucleus interaction, and, eventually, also to extract information about neutron distributions in nuclei. | nuclear structure uncertainties in coherent elastic neutrino-nucleus scattering |
the deep underground neutrino experiment (dune) is a 40-kton underground liquid argon time-projection-chamber detector that will have unique sensitivity to the electron flavor component of a core-collapse supernova neutrino burst. we present expected capabilities of dune for measurements of neutrinos in the few-tens-of-mev range relevant for supernova detection and the corresponding sensitivities to neutrino physics and supernova astrophysics. recent progress and some outstanding issues will be highlighted. | supernova burst observations with dune |
gadolinium-loading of large water cherenkov detectors is a prime method for the detection of the diffuse supernova neutrino background (dsnb). while the enhanced neutron tagging capability greatly reduces single-event backgrounds, correlated events mimicking the ibd coincidence signature remain a potentially harmful background. neutral-current (nc) interactions of atmospheric neutrinos potentially dominate the dsnb signal especially in the low-energy range of the observation window that reaches from about 12 to 30 mev. | cnns for enhanced background discrimination in dsnb searches in large-scale water-gd detectors |
with the aim of improving our knowledge about their nature, we conduct a comparative study on a sample of long-rising type ii supernovae (sne) resembling sn 1987a. to do so, we deduce various scaling relations from different analytic models of h-rich sne, discussing their robustness and feasibility. then, we use the best relations in terms of accuracy to infer the sn progenitor's physical properties at the explosion for the selected sample of sn 1987a-like objects, deriving energies of ~0.5-15 foe, radii of ~0.2-100 × 1012 cm, and ejected masses of ~15-55 m⊙. although the sample may be too small to draw any final conclusion, these results suggest that (i) sn 1987a-like objects have parameters at explosion covering a wide range of values; (ii) the main parameter determining their distribution is the explosion energy; and (iii) a high-mass (≳ 30 m⊙) and high-energy (≳ 10 foe) tail of events, linked to extended progenitors with radii at explosion ~1013-1014 cm, challenge standard theories of neutrino-driven core-collapse and stellar evolution. we also find a correlation between the amount of 56ni in the ejecta of the sn 1987a-like objects and the spectrophotometric features of the sn at maximum, which may represent a tool for estimating the amount of 56ni in the sn ejecta without having information on the tail luminosity. | long-rising type ii supernovae resembling supernova 1987a - i. a comparative study through scaling relations |
we present the new code nada-fld to solve multidimensional neutrino-hydrodynamics in full general relativity (gr) in spherical polar coordinates. the energy-dependent neutrino transport assumes the flux-limited diffusion approximation and evolves the neutrino energy densities measured in the frame comoving with the fluid. operator splitting is used to avoid multidimensional coupling of grid cells in implicit integration steps involving matrix inversions. terms describing lateral diffusion and advection are integrated explicitly using the allen-cheng or the runge-kutta-legendre method, which remain stable even in the optically thin regime. we discuss several toy-model problems in one and two dimensions to test the basic functionality and individual components of the transport scheme. we also perform fully dynamic core-collapse supernova (ccsn) simulations in spherical symmetry. for a newtonian model, we find good agreement with the m1 code alcar, and for a gr model, we reproduce the main effects of gr in ccsne already found by previous works. | nada-fld: a general relativistic, multidimensional neutrino-hydrodynamics code employing flux-limited diffusion |
the thermal quasiparticle random-phase approximation is combined with the skyrme energy density functional method (skyrme-tqrpa) to study the response of a hot nucleus to an external perturbation. for the sample nuclei 56fe and 82ge, the skyrme-tqrpa is applied to analyze thermal effects on the strength function of charge-neutral gamow-teller transitions, which dominate neutrino-nucleus reactions at eν≲20 mev. for the relevant supernova temperatures we calculate the cross sections for inelastic neutrino scattering. we also apply the method to examine the rate of neutrino-antineutrino pair emission by hot nuclei. the cross sections and rates are compared with those obtained earlier from the tqrpa calculations based on the phenomenological quasiparticle-phonon model hamiltonian. for inelastic neutrino scattering on 56fe we also compare the skyrme-tqrpa results to those obtained earlier from a hybrid approach that combines shell-model and rpa calculations. | thermal quasiparticle random-phase approximation with skyrme interactions and supernova neutral-current neutrino-nucleus reactions |
the possible fermi detection of an electromagnetic counterpart to the double black hole merger gw150914 has inspired many theoretical models, some of which propose that the holes spiralled together inside a massive star. however, we show that the heat produced by the dynamical friction on such black hole orbits can exceed the stellar binding energy by a large factor, which means that this heat could destroy the star. the energy scale of the explosion and the terminal velocity of the gas can be much larger than those in conventional supernovae. if the star unbinds before the merger, it would be hard for enough gas to remain near the holes at the merger to produce a gamma-ray burst, and this consideration should be taken into account when models are proposed for electromagnetic counterparts to the coalescence of two stellar-mass black holes. we find that only when the two black holes form very close to the centre can the star certainly avoid destruction. in that case, dynamical friction can make the black holes coalesce faster than they would in vacuum, which leads to a modification of the gravitational waveform that is potentially observable by advanced ligo. | energetic constraints on electromagnetic signals from double black hole mergers |
the next time a core-collapse supernova (sn) explodes in our galaxy, various detectors will be ready and waiting to detect its emissions of gravitational waves (gws) and neutrinos. current numerical simulations have successfully introduced multi-dimensional effects to produce exploding sn models, but thus far the explosion mechanism is not well understood. in this paper, we focus on an investigation of progenitor core rotation via comparison of the start time of gw emission and that of the neutronization burst. the gw and neutrino detectors are assumed to be, respectively, the kagra detector and a co-located gadolinium-loaded water cherenkov detector, either egads or gadzooks!. our detection simulation studies show that for a nearby sn (0.2 kpc) we can confirm the lack of core rotation close to 100% of the time, and the presence of core rotation about 90% of the time. using this approach there is also the potential to confirm rotation for considerably more distant milky way sn explosions. | probing the rotation of core-collapse supernova with a concurrent analysis of gravitational waves and neutrinos |
using full boltzmann neutrino transport, we performed 2d core-collapse supernova simulations in axisymmetry for two progenitor models with 11.2 and 15.0 m ⊙, both rotational and nonrotational. we employed the results obtained in the early post-bounce phase (t ≲ 20 ms) to assess performance under rapid rotation of some closure relations commonly employed in the truncated moment method. we first made a comparison in 1d under spherical symmetry, though, of the eddington factor p defined in the fluid rest frame (fr). we confirmed that the maximum entropy closure for the fermionic distribution (mefd) performs better than others near the proto-neutron star surface, where p < 1/3 occurs, but does not work well even in 1d when the phase-space occupancy satisfies e < 0.5 together with p < 1/3, the condition known to be not represented by mefd. for the 2d models with the rapid rotation, we employed the principal-axis analysis of the eddington tensor. we paid particular attention to the direction of the longest principal axis. we observed in fr that it is aligned neither with the radial direction nor with the neutrino flux in 2d, particularly so in convective and/or rapidly rotating regions, the fact not accommodated in the moment method. we repeated the same analysis in the laboratory frame and found again that the direction of the longest principal axis is not well reproduced by mefd because the interpolation between the optically thick and thin limits is not very accurate in this frame. | principal-axis analysis of the eddington tensor for the early post-bounce phase of rotational core-collapse supernovae |
we present neutrino-transport hydrodynamic simulations of electron-capture supernovae (ecsne) in flash with new two-dimensional (2d) collapsing progenitor models. these progenitor models feature the 2d modelling of oxygen-flame propagation until the onset of core collapse. we perform axisymmetric simulations with six progenitor models that, at the time of collapse, span a range of propagating flame front radii. for comparison, we also perform a simulation with the same set-up using the canonical, spherically symmetrical progenitor model n8.8. we found that the variations in the progenitor models inherited from simulations of stellar evolution and flame propagation do not significantly alter the global properties of the neutrino-driven ecsn explosion, such as the explosion energy (~1.36-1.48 × 1050 erg) and the mass (~0.017-0.018 m⊙) and composition of the ejecta. due to aspherical perturbations induced by the 2d flame, the ejecta contains a small amount (≲1.8 × 10-3 m⊙) of low-ye (0.35 < ye < 0.4) component. the baryonic mass of the protoneutron star is ~1.34 m⊙ (~1.357 m⊙) with the new (n8.8) progenitor models when simulations end at ~400 ms and the discrepancy is due to updated weak-interaction rates in the progenitor evolutionary simulations. our results reflect the nature of ecsn progenitors containing a strongly degenerate oxygen-neon-magnesium (onemg) core and suggest a standardized ecsn explosion initialized by onemg core collapse. moreover, we carry out a rudimentary three-dimensional simulation and find that the explosion properties are fairly compatible with the 2d counterpart. our paper facilitates a more thorough understanding of ecsn explosions following the onemg core collapse, though more three-dimensional simulations are still needed. | hydrodynamic simulations of electron-capture supernovae: progenitor and dimension dependence |
resonant interactions between neutrinos from a galactic supernova and dark matter particles can lead to a sharp dip in the neutrino energy spectrum. due to its excellent energy resolution, measurement of this effect with the juno experiment can provide evidence for such couplings. we discuss how juno may confirm or further constrain a model where scalar dark matter couples to active neutrinos and another fermion. | juno sensitivity to resonant absorption of galactic supernova neutrinos by dark matter |
a high-statistics measurement of the neutrinos from a galactic core-collapse supernova is extremely important for understanding the explosion mechanism, and studying the intrinsic properties of neutrinos themselves. in this paper, we explore the possibility to constrain the absolute scale of neutrino masses mν via the detection of galactic supernova neutrinos at the jiangmen underground neutrino observatory (juno) with a 20 kiloton liquid-scintillator detector. in assumption of a nearly-degenerate neutrino mass spectrum and a normal mass ordering, the upper bound on the absolute neutrino mass is found to be mν < (0.83 ± 0.24) ev at the 95% confidence level for a typical galactic supernova at a distance of 10 kpc, where the mean value and standard deviation are shown to account for statistical fluctuations. for comparison, we find that the bound in the super-kamiokande experiment is mν < (0.94 ± 0.28) ev at the same confidence level. however, the upper bound will be relaxed when the model parameters characterizing the time structure of supernova neutrino fluxes are not exactly known, and when the neutrino mass ordering is inverted. | constraining absolute neutrino masses via detection of galactic supernova neutrinos at juno |
a comparative study of the λ hyperon equations of state of banik, hempel and banyopadhyay (bhb), banik et al., and shen et al. (denoted as hshen λ) for core-collapse supernova (ccsn) simulations is carried out in this work. the dynamical evolution of a protoneutron star (pns) into a black hole is investigated in ccsn simulations in the general relativistic one-dimensional code using the {bhb}{{λ }}φ and hshen λ equation of state (eos) tables and different progenitor models from woosley & heger. radial profiles of the mass fractions of baryons, the density, as well as the temperature in the pns at different moments in time, are compared for both eos tables. the behavior of the central density of the pns with time is demonstrated for these two λ hyperon eos tables and compared with their corresponding nuclear eos tables. it is observed that the black hole formation time is higher in the {bhb}{{λ }}φ case than in the hshen λ eos case for the entire set of progenitor models adopted here, because the repulsive λ-λ interaction makes the {bhb}{{λ }}φ eos stiffer. neutrino emission with the λ hyperon eos ceases earlier than that of its nuclear counterpart. the long-duration evolution of the shock radius and the gravitational mass of the pns after a successful supernova explosion with enhanced neutrino heating are studied with the {bhb}{{λ }}φ eos and s20wh07 progenitor model. the pns is found to remain stable for 4 s and might evolve into a cold neutron star. | a comparative study of hyperon equations of state in supernova simulations |
the importance of microphysical inputs from laboratory nuclear experiments and theoretical nuclear structure calculations in the understanding of core-collapse dynamics and the subsequent supernova explosion is largely recognized in the recent literature. in this work, we analyze the impact of the masses of very neutron-rich nuclei on the matter composition during collapse and the corresponding electron-capture rate. to this end, we introduce an empirical modification of the popular duflo-zuker mass model to account for possible shell quenching far from stability. we study the effect of this quenching on the average electron-capture rate. we show that the pre-eminence of the closed shells with n =50 and n =82 in the collapse dynamics is considerably decreased if the shell gaps are reduced in the region of 78ni and beyond. as a consequence, local modifications of the overall electron-capture rate of up to 30% can be expected, depending on the strength of magicity quenching. this finding has potentially important consequences on the entropy generation, the neutrino emissivity, and the mass of the core at bounce. our work underlines the importance of new experimental measurements in this region of the nuclear chart, the most crucial information being the nuclear mass and the gamow-teller strength. reliable microscopic calculations of the associated elementary rate, in a wide range of temperatures and electron densities, optimized on these new empirical information, will be additionally needed to get quantitative predictions of the collapse dynamics. | modification of magicity toward the dripline and its impact on electron-capture rates for stellar core collapse |
the liquid argon time projection chambers (lartpcs) are a choice for the next generation of large neutrino detectors due to their optimal performance in particle tracking and calorimetry. the detection of argon scintillation light plays a crucial role in the event reconstruction as well as the time reference for non-beam physics such as supernovae neutrino detection and baryon number violation studies. in this contribution, we present the current r&d work on the arapuca (argon r&d advanced program at unicamp), a light trap device to enhance ar scintillation light collection and thus the overall performance of lartpcs. the arapuca working principle is based on a suitable combination of dichroic filters and wavelength shifters to achieve a high efficiency in light collection. we discuss the operational principles, the last results of laboratory tests and the application of the arapuca as the alternative photon detection system in the protodune detector. | increasing the efficiency of photon collection in lartpcs: the arapuca light trap |
recent hydrodynamical simulations of core-collapse supernova (ccsn) evolution have highlighted the importance of thorough control over the microscopic physics responsible for such internal processes as neutrino heating. in particular, it has been suggested that modifications to the neutrino-nucleon elastic cross section can potentially play a crucial role in producing successful ccsn explosions. one possible source of such corrections can be found in a nonzero value for the nucleon's strange helicity content δ s . in the present analysis, however, we show that theoretical and experimental progress over the past decade has suggested a comparatively small magnitude for δ s , such that its sole effect is not sufficient to provide the physics leading to ccsn explosions. | role of nucleon strangeness in supernova explosions |
some massive stars end their lives as \textit{failed} core-collapse supernovae (ccsne) and become black holes (bhs). although in this class of phenomena the stalled supernova shock is not revived, the outer stellar envelope can still be partially ejected. this occurs because the hydrodynamic equilibrium of the star is disrupted by the gravitational mass loss of the protoneutron star (pns) due to neutrino emission. we develop a simple model that emulates pns evolution and its neutrino emission and use it to simulate failed ccsne in spherical symmetry for a wide range of progenitor stars. our model allows us to study mass ejection of failed ccsne where the pns collapses into a bh within $\sim100\,{\rm ms}$ and up to $\sim10^6\,{\rm s}$. we perform failed ccsne simulations for 262 different pre-sn progenitors and determine how the energy and mass of the ejecta depend on progenitor properties and the equation of state (eos) of dense matter. in the case of a future failed ccsn observation, the trends obtained in our simulations can be used to place constraints on the pre-sn progenitor characteristics, the eos, and on pns properties at bh formation time. | a parameterized neutrino emission model to study mass ejection in failed core-collapse supernovae |
we present the first ab initio lattice calculations of spin and density correlations in hot neutron matter using high-fidelity interactions at next-to-next-to-next-to-leading order (n3lo) in chiral effective field theory. these correlations have a large impact on neutrino heating and shock revival in core-collapse supernovae and are encapsulated in functions called structure factors. unfortunately, calculations of structure factors using high-fidelity chiral interactions were well out of reach using existing computational methods. in this work, we solve the problem using a computational approach called the rank-one operator (ro) method. the ro method is a general technique with broad applications to simulations of fermionic many-body systems. it uses the fact that the determinant of a matrix composed of rank-one operators is at most linear in each operator coefficient. using the ro method, we compute the vector and axial static structure factors for hot neutron matter as a function of temperature and density. the ab initio lattice results are in good agreement with virial expansion calculations at low densities and can be used to calibrate random phase approximation codes commonly used to estimate many-body effects on the neutrino opacity in core-collapse supernovae. | structure factors for hot neutron matter from ab initio lattice simulations with high-fidelity chiral interactions |
time delay in schwarzschild spacetime for null and timelike signals with arbitrary velocity v is studied. the total travel time tif is evaluated both exactly and approximately in the weak field limit, with the result given as functions of signal velocity, source-lens, and lens-observer distances, angular position of the source and lens mass. two time delays, δ tv between signals with different velocities but coming from same side of the lens and δ tp between signals from different sides of the lens, as well as the difference δ tp v between two δ tp's are calculated. these time delays are applied to the gravitational-lensed supernova neutrinos and gravitational waves (gw). it is shown that the δ tv between different mass eigenstates of supernova neutrinos can be related to the mass square difference of these eigenstates and therefore could potentially be used to discriminate neutrino mass orderings, while the difference δ tp v between neutrino and optical signals can be correlated with the absolute mass of neutrinos. the formula for time delay in a general lens mass profile is derived and the result is applied to the singular isothermal sphere case. for gws, it is found that the difference δ tp v between gw and grb can only reach 1.45 ×10-5 second for very large source distance (2 ×104 [mpc ] ) and source angle (10 [as]) if vgm=(1 -3 ×10-15)c . this time difference is at least three orders smaller than uncertainties in time measurement of the recently observed gw/grb signals and thus calls for improvement if δ tp v is to be used to further constrain the gw velocity. | time delay of timelike particles in gravitational lensing of the schwarzschild spacetime |
background: nuclear pasta matter, emerging due to the competition between the long-range coulomb force and the short-range strong force, is believed to be present in astrophysical scenarios, such as neutron stars and core-collapse supernovae. its structure can have a high impact, e.g., on neutrino transport or the tidal deformability of neutron stars. purpose: we investigate the impact of nuclear pasta on neutrino interactions and compare the results to uniform matter. method: we calculate the elastic and inelastic static structure factors for nuclear pasta matter, using density functional theory (dft), which contain the main nuclear input for neutrino scattering. results: each pasta structure leaves a unique imprint in the elastic structure factor and it is largely enhanced. the inelastic structure factors are very similar for all configurations. conclusion: nuclear pasta has a noticeable impact on neutrino neutral-current scattering opacities. while for inelastic reactions the cross section is reduced, the elastic coherent scattering increases dramatically. the effect can be of importance for the cooling of neutron stars as well as for core-collapse supernova models. | survey of nuclear pasta in the intermediate-density regime: structure functions for neutrino scattering |
in this paper, we investigate the constraints on the total neutrino mass ∑mν in a cosmological model in which dark energy and neutrinos are coupled such that the mass of the neutrinos and potentials are function of the scalar field as mν=m0exp(α/ϕ mpl) and v (ϕ ) =mpl4exp(-λ/ϕ mpl) respectively. the observational data used in this work include the type ia supernovae (sn) observation (pantheon compilation), cc, cmb and bao data. we find that the neutrino mass is tightly constrained to ∑mν<0.125 ev 95% confidence level (c.l.) and the effective extra relativistic degrees of freedom to be neff=2 .955-0.12+0.11 68% c.l in agreement with the standard model prediction neff=3.046 , matter-radiation equality, zeq=338925+24 (68% c.l). these results are in good agreement with the results of planck 2018 where the limit of the total neutrino mass is ∑mν<0.12 ev (95% c.l., tt, te, ee + lowe + lensing + bao) , neff=2 .99-0.17+0.17 (68% c.l., tt, te, ee + lowe + lensing + bao) and zeq=338721+21 (68% c.l tt, te, ee + lowe + lensing + bao). | constraining neutrino mass in dark energy dark matter interaction and comparison with 2018 planck results |
we investigate whether the recent ultra-high energy neutrino events detected at the icecube neutrino observatory could come from the decay of charmed mesons produced within the mildly relativistic jets of supernova-like astrophysical sources. we demonstrate that the allowed region in the astrophysical and qcd parameter spaces permit an explanation of the 5.7σ excess of neutrinos observed by icecube in the energy range 30 tev-2 pev as a diffuse flux of neutrinos produced in such slow-jet supernovae. we discuss the theoretical uncertainties inherent in the evaluation of charm production in high energy hadronic collisions, as well as some of the astrophysical uncertainties associated with slow-jet supernova sources. these sources result in a diffuse neutrino spectrum that exhibits a sharp drop at energies above a few pev. we incorporate the effect of energy dependence in the spectrum-weighted charm production and decay cross sections and show that this has a very significant effect on the shape, magnitude and cutoff energies for the diffuse neutrino flux. | charm decay in slow-jet supernovae as the origin of the icecube ultra-high energy neutrino events |
we study the role of light nuclear clusters in simulations of core-collapse supernovae. expressions for the reaction rates are developed for a large selection of charged current absorption and scattering processes with light clusters. medium modifications are taken into account at the mean-field level. we explore the possible impact on the supernova dynamics and the neutrino signal during the mass accretion phase prior to the possible explosion onset as well as during the subsequent protoneutron star deleptnoization after the explosion onset has been launched. | expected impact from weak reactions with light nuclei in corecollapse supernova simulations |
some massive stars end their lives as failed core-collapse supernovae (ccsne) and become black holes (bhs). although in this class of phenomena the stalled supernova (sn) shock is not revived, the outer stellar envelope can still be partially ejected. this occurs because the hydrodynamic equilibrium of the star is disrupted by the gravitational mass loss of the protoneutron star (pns) due to neutrino emission. we develop a simple parameterized model that emulates pns evolution and its neutrino emission and use it to simulate failed ccsne in spherical symmetry for a wide range of progenitor stars. our model allows us to study mass ejection of failed ccsne where the pns collapses into a bh within ~100 ms and up to ~106 s. we perform failed ccsne simulations for 262 different pre-sn progenitors and determine how the energy and mass of the ejecta depend on progenitor properties and the equation of state (eos) of dense matter. in the case of a future failed ccsn observation, the trends obtained in our simulations can be used to place constraints on the pre-sn progenitor characteristics, the eos, and on pns properties at bh formation time. | a parameterized neutrino emission model to study mass ejection in failed core-collapse supernovae |
snowglobes (supernova observatories with globes) computes interaction rates and distributions of observed quantities for supernova burst neutrinos in common detector materials. the code provides a very simple and fast code and data package for tests of observability of physics signatures in current and future detectors, and for evaluation of relative sensitivities of different detector configurations. the event estimates are made using available cross-sections and parameterized detector responses. water, argon, scintillator and lead-based configurations are included. the package makes use of globes (ascl:2109.018). snowglobes is not intended to replace full detector simulations; however output should be useful for many types of studies, and simulation results can be incorporated. | snowglobes: supernova observatories with globes |
we demonstrate that observations of the gravitational memory from core collapse supernovae at future deci-hz interferometers enable time-triggered searches of supernova neutrinos at mt-scale detectors. achieving a sensitivity to characteristic strains of at least ∼10-25 at f ≃0.3 hz —e.g., by improving the noise of decigo by one order of magnitude—will allow robust time triggers for supernovae at distances d ∼40 - 300 mpc , resulting in a nearly background-free sample of ∼3 - 70 neutrino events per mt per decade of operation. this sample would bridge the sensitivity gap between rare galactic supernova bursts and the cosmological diffuse supernova neutrino background, allowing detailed studies of the neutrino emission of supernovae in the local universe. | memory-triggered supernova neutrino detection |
the behaviour and properties of neutrinos in non-uniform nuclear matter, surrounded by electrons and other neutrinos are studied in the protoneutron star early stage characterized by trapped neutrinos. the nuclear matter itself is modelled by a relativistic mean-field approach, and models with both constant couplings and density-dependent couplings are considered. the so-called nuclear pasta phases at sub-saturation densities, described using the thomas-fermi approximation and solved in a wigner-seitz cell, are included in the calculation. we obtain the neutrino total cross section and mean free path, taking into account scattering and absorption processes and we compare the final results obtained with different parametrizations. the solution for this problem is important for the understanding of neutrino diffusion in a newly born neutron star after a supernovae explosion. it is shown that the pasta phase will increase the neutrino mean free path by as much as an order of magnitude, therefore contributing for shorter emission time-scales. | neutrino diffusion in the pasta phase matter within the thomas-fermi approach |
we examine the protoneutron star (pns) stability in this study by solving the radial oscillation equations. for this purpose, we adopt the numerical results of a massive pns towards the black hole formation obtained by spherically symmetric numerical simulations for a core-collapse supernova with general relativistic neutrino-radiation hydrodynamics. we find that the pnss are basically stable in their evolution against the radial perturbations, while the pns finally becomes unstable before the apparent horizon appears inside the pns. we also examine the gravitational wave frequencies from the pns with the relativistic cowling approximation. then, we derive the empirical formula for the f-mode frequency, which weakly depends on the pns models. this kind of universality tells us the pns property, which is a combination of the pns mass and radius in this study, once one would observe the f-mode gravitational waves. | stability of the protoneutron stars towards black hole formation |
neutron stars are born out of core-collapse supernovae, and they are imparted natal kicks at birth as a consequence of asymmetric ejection of matter and possibly neutrinos. unless the force resulting from the kicks is exerted exactly at their center, it will also cause the neutron star to rotate. in this paper, we discuss the possibility that neutron stars may receive off-center natal kicks at birth, which imprint a natal rotation. in this scenario, the observed pulsar spin and transverse velocity in the galaxy are expected to correlate. we develop a model of the natal rotation imparted to neutron stars and constrain it by the observed population of pulsars in our galaxy. when considering a single-kick position parameter, we find that the location of the off-center kick is ${r}_{\mathrm{kick}}={2.03}_{-1.69}^{+3.74}$ km at 90% confidence, and is robust when considering pulsars with different observed periods, transverse velocities, and ages. nonetheless, the model encounters challenges in effectively fitting the data, particularly at small transverse velocities, prompting the exploration of alternative models that include more complex physics. our framework could be used as a guide for core-collapse simulations of massive stars. | neutron star kicks and implications for their rotation at birth |
observations with next-generation ground-based detectors further enhanced with multi-messenger (electromagnetic and neutrino) detections will allow us to probe new extreme astrophysics. target sources included: core-collapse supernovae, continuous emission from isolated or accreting neutron stars, and bursts from magnetars and other pulsars. | the yet-unobserved multi-messenger gravitational-wave universe |
baryonic matter close to the saturation density is very likely to present complex inhomogeneous structures collectively known under the name of nuclear pasta phase. at finite temperature, the different geometric structures are expected to coexist with potential consequences on the neutron star crust conductivity and neutrino transport in supernova matter. in the framework of a statistical multicomponent approach, we calculate the composition of matter in the pasta phase considering density, proton fraction, and geometry fluctuations. using a realistic energy functional from relativistic mean-field theory and a temperature- and isospin-dependent surface tension fitted from thomas-fermi calculations, we show that different geometries can coexist in a large fraction of the pasta phase, down to temperatures of the order of the crystallization temperature of the neutron star crust. quantitative estimates of the charge fluctuations are given. | fluctuations in the nuclear pasta phase |
a major part of the energy released upon the gravitational collapse of massive-star cores is carried away by neutrinos. neutrinos play a crucial role in collapsing supernovae (sne). at the present time, mathematical models of core-collapse sne are based on multidimensional gas dynamics and thermonuclear reactions, whereas the neutrino transport is frequently treated in simplified way. an accurate analysis of neutrinos in a spherically symmetric gravitational collapse is performed on the basis of boltzmann kinetic equations including all weak-interaction reactions with exact quantum-mechanical matrix elements. the role of multidimensional effects is studied bymeans of multidimensional gas dynamics allowing for the neutrino transport via diffusion treated by employing flux limiters. the possibility of largescale convection, which is of interest both from the point of view of explaining a type ii supernova (sn) and from the point of view of implementing an experiment aimed at detecting possible energetic (≳10 mev) neutrinos from an sn, is discussed. thermonuclear burning leads to the explosion of a type i sn. a hot central region and the subsequent large-scale convection may also play an important role in the sn mechanism. if neutrinos and convection play a key role for a type ii sn, then, in order to explain gamma radiation from product radioactive elements, convection is of importance in the case of sne belonging to both types. in addition, convection may be important for bright type i sne. original methods are presented for multidimensional gas dynamics involving thermonuclear burning and for multitemperature gas dynamics involving radiative transfer. | supernova-explosion mechanism involving neutrinos |
it is known that muons are scarce just after the birth of a proto-neutron star via a supernova explosion, but get more abundant as the proto-neutron star cools via neutrino emissions on the kelvin-helmholtz timescale. we evaluate all the relevant rates of the neutrino interactions with muons at different times in the proto-neutron star cooling. we are particularly interested in the late phase ($t \gtrsim 10 \operatorname{s}$), which will be accessible in the next galactic supernova but has not been studied well so far. we calculate both leptonic and semi-leptonic processes, for the latter of which we also pay attention to the form factors with their dependence on the transferred momentum as well as to the modification of the dispersion relations for nucleons on the mean field level. we find that the flavor-exchange reactions νe + μ- → νμ + e- and $\bar{\nu }_{\mu } + \mu ^- \rightarrow \bar{\nu }_e + e^-$ can be dominant, particularly at low energies, over the capture of νe on neutron and the scatterings of $\bar{\nu }_{\mu }$ on nucleons as the opacity sources for these species, and that the inverse muon decay $\bar{\nu }_e + \nu _{\mu } + e^- \leftrightarrows \mu ^-$ can overwhelm the scatterings of $\bar{\nu }_e$ and νμ on nucleons again at low energies. at high energies, on the other hand, the corrections in the semi-leptonic processes mentioned above are more important. we also show the non-trivial energy and angular dependencies of the flavor-exchange reactions and the inverse muon decay. in the study of the diffusion coefficients from these reactions, we find that $\bar{\nu }_{\mu }$ is most affected. these pieces of information are indispensable for numerical computations and the interpretation of their results for proto-neutron star cooling, particularly at the very late phase. | leptonic and semi-leptonic neutrino interactions with muons in proto-neutron star cooling |
we consider the neutrino self-energy in a background composed of a scalar particle and a fermion using a simple model for the coupling of the form λ f¯rνlϕ . the results are useful in the context of dark matter-neutrino interaction models in which the scalar and/or fermion constitute the dark matter. the corresponding formulas for models in which the scalar particle couples to two neutrinos via a coupling of the form λ(ν ν ϕ )ν¯rcνlϕ are then obtained as a special case. in the presence of these interactions there can be new contributions to the neutrino effective potential and index of refraction in the context of neutrino collective oscillations in a supernova and in the early universe hot plasma before neutrino decoupling. the formulas obtained here can be used to estimate those effects and/or put limits on the model parameters based on the contribution that such interactions can have in those contexts. a particular feature of the results is that the contribution to the neutrino self-energy or effective potential in a neutrino background due to the ν ν ϕ coupling is proportional to the antineutrino-neutrino asymmetry (nν ¯-nν), in contrast to the standard z contribution which is proportional to (nν-nν ¯). therefore the two contributions tend to cancel. if the cancellation is significant, it is conceivable that the o (1 /mϕ4) terms give the dominant contribution. alternatively, a limit can be set by requiring that the contribution of the ν ν ϕ interaction to the neutrino effective potential does not cancel the standard contribution in an appreciable way. | neutrino effective potential in a fermion and scalar background |
in a previous work [haas et al., phys. plasmas 23, 012104 (2016)], a new model was introduced, taking into account the role of the fermi weak force due to neutrinos coupled to magnetohydrodynamic plasmas. the resulting neutrino-magnetohydrodynamics was investigated in a particular geometry associated with the magnetosonic wave, where the ambient magnetic field and the wavevector are perpendicular. the corresponding fast, short wavelength neutrino beam instability was then obtained in the context of supernova parameters. the present communication generalizes these results, allowing for arbitrary direction of wave propagation, including fast and slow magnetohydrodynamic waves and the intermediate cases of oblique angles. the numerical estimates of the neutrino-plasma instabilities are derived in extreme astrophysical environments where dense neutrino beams exist. | instabilities and propagation of neutrino magnetohydrodynamic waves in arbitrary direction |
under the assumption that jets explode core collapse supernovae (ccsne) in a negative jet feedback mechanism (jfm), this paper shows that rapidly rotating neutron stars are likely to be formed when the explosion is very energetic. under the assumption that an accretion disk or an accretion belt around the just-formed neutron star launch jets and that the accreted gas spins-up the just-formed neutron star, i derive a crude relation between the energy that is stored in the spinning neutron star and the explosion energy. this relation is (e ns-spin/e exp) ≈ e exp/1052 erg; it shows that within the frame of the jfm explosion model of ccsne, spinning neutron stars, such as magnetars, might have significant energy in super-energetic explosions. the existence of magnetars, if confirmed, such as in the recent super-energetic supernova gaia16apd, further supports the call for a paradigm shift from neutrino-driven to jet-driven ccsn mechanisms. | the magnetar model of the superluminous supernova gaia16apd and the explosion jet feedback mechanism |
investigations of dense neutrino cloud evolution through quantum kinetic equations led to the possibility of "fast flavor" (ff) processes. it is shown here that the usual quantum kinetic equations, while signaling the instabilities that make some instances of ff possible, are being erroneously interpreted. approaching the subject directly from the quantum field theory that defines the standard model shows the computational structures in most of the recent ff literature to be completely invalid. our revisions also underlie what promise to be new early universe applications and a general result for relic supernova neutrinos that could be tested as a feature of the diffuse neutrino spectrum. | fast flavor evolution in dense neutrino systems, as described in quantum field theory |
core-collapse supernovae are a useful laboratory to probe the nature of exotic particles. if axionlike particles (alps) are produced in supernovae, they can affect the transfer of energy and leave traces in observational signatures. in this work, we present results from two-dimensional supernova models including the effects of the production and the absorption of alps that couple with photons. it is found that the additional heating induced by alps can enhance the diagnostic energy of explosion, ediag. for example, for moderate alp-photon coupling, we find explosion energies ∼0.6 ×1051 erg compared to our reference model without alps of ∼0.4 ×1051 erg in the first ∼0.5 s postbounce explored in this work. our findings indicate that when the coupling constant is sufficiently high, the neutrino luminosities and mean energies are decreased because of the additional cooling of the proto-neutron star via alps. the gravitational wave amplitude is also reduced because the mass accretion on the proto-neutron star is suppressed. although the alp-photon coupling can foster explodability, including enhancing the explosion energy closer to recent observations, more long-term simulations in three spatial dimensions are needed to draw robust conclusions. | multimessenger signals of heavy axionlike particles in core-collapse supernovae: two-dimensional simulations |
the observation of electromagnetic counterparts to both high energy neutrinos and gravitational waves marked the beginning of a new era in astrophysics. the multi-messenger approach allows us to gain new insights into the most energetic events in the universe such as gamma-ray bursts, supernovas, and black hole mergers. real-time multi-messenger alerts are the key component of the observational strategies to unravel the transient signals expected from astrophysical sources. focusing on the high-energy regime, we present a historical perspective of multi-messenger observations, the detectors and observational techniques used to study them, the status of the multi-messenger alerts and the most significant results, together with an overview of the future prospects in the field. | high-energy alerts in the multi-messenger era |
the energy radiated in supernova neutrinos is a fundamental quantity that is closely related to the gravitational binding energy of a neutron star. recently the tidal deformability of neutron stars was constrained by gravitational wave observations. by considering several equations of state, we find a strong correlation between the tidal deformability and neutron star binding energy. we use this correlation to sharpen predictions of the binding energy of neutron stars and the total neutrino energy in supernovae. we find a minimum binding energy for a neutron star formed in a supernova of ∼1.5 ×1053 ergs . should the neutrino energy in a supernova be significantly below this value, it would strongly suggest new unobserved particles are carrying away some of the supernova energy. alternatively, if the neutrino energy is observed above ∼6 ×1053 ergs , it would strongly imply the formation of a (perhaps surprisingly) massive neutron star. | total energy in supernova neutrinos and the tidal deformability and binding energy of neutron stars |
core-collapse supernova explosions are driven by a central engine that converts a small fraction of the gravitational binding energy released during core collapse to outgoing kinetic energy. the suspected mode for this energy conversion is the neutrino mechanism, where a fraction of the neutrinos emitted from the newly formed protoneutron star are absorbed by and heat the matter behind the supernova shock. accurate neutrino-matter interaction terms are crucial for simulating these explosions. in this proceedings for iaus 331, sn 1987a, 30 years later, we explore several corrections to the neutrino-nucleon scattering opacity and demonstrate the effect on the dynamics of the core-collapse supernova central engine via two dimensional neutrino-radiation-hydrodynamics simulations. our results reveal that the explosion properties are sensitive to corrections to the neutral-current scattering cross section at the 10-20% level, but only for densities at or above ~1012 g cm-3. | core-collapse supernova simulations including neutrino interactions from the virial eos |
black hole formation in a core-collapse supernova is expected to lead to a distinctive, abrupt drop in neutrino luminosity due to the engulfment of the main neutrino-producing regions as well as the strong gravitational redshift of those remaining neutrinos which do escape. previous analyses of the shape of the cutoff have focused on specific trajectories or simplified models of bulk neutrino transport. in this article, we integrate over simple null geodesics to investigate potential effects on the cutoff profile of including all neutrino emission angles from a collapsing surface in the schwarzschild metric, and from a contracting equatorial mass ring in the kerr metric. we find that the nonradial geodesics contribute to a softening of the cutoff in both cases. in addition, extreme rotation introduces significant changes to the shape of the tail which may be observable in future neutrino detectors, or combinations of detectors. | nonradial neutrino emission upon black hole formation in core collapse supernovae |
we discuss the possibility of reconstructing the newly formed proto-neutron star radius from the late time neutrino signal. a black-body emission is assumed for the neutron star cooling phase. we parametrize the neutrino time-integrated fluxes based on simulations of roberts and reddy. a likelihood analysis of the inverse-beta decay and elastic scattering events in hyper-kamiokande is performed in both three flavor and an effective one flavor scenario. we show that the precision achievable in the radius reconstruction strongly depends on a correlation with the pinching parameter and therefore the corresponding prior. although this correlation hinders the precise measurement of the newly formed neutron star radius, it could help measure the pinching parameters with good accuracy in view of the current constraints on neutron star radius, or if the neutron star radius is precisely measured. | late time supernova neutrino signal and proto-neutron star radius |
core-collapse supernovae produce an intense burst of electron antineutrinos in the few-tens-of-mev range. several large liquid scintillator-based detectors (llsd) are currently operated worldwide, being very effective for low energy antineutrino detection through the inverse beta decay (ibd) process. in this article, we develop a procedure for the prompt extraction of the supernova location by revisiting the details of ibd kinematics over the broad energy range of supernova neutrinos. combining all current scintillator-based detector, we show that one can locate a canonical supernova at 10 kpc with an accuracy of 45 degrees (68% c.l.). after the addition of the next generation of scintillator-based detectors, the accuracy could reach 12 degrees (68% c.l.), therefore reaching the performances of the large water čerenkov neutrino detectors. we also discuss a possible improvement of the supernova early warning system (snews) inter-experiment network with the implementation of a directionality information in each experiment. finally, we discuss the possibility to constrain the neutrino energy spectrum as well as the mass of the newly born neutron star with the llsd data. | prompt directional detection of galactic supernova by combining large liquid scintillator neutrino detectors |
core-collapse supernovae are fascinating astrophysical objects for multimessenger studies. gravitational waves are expected to play an important role in the supernova explosion mechanism. unfortunately, their modeling is challenging, due to the stochastic nature of the dynamics and the vast range of possible progenitors. therefore, the gravitational wave detection from these objects is still elusive with already advanced detectors. low-energy neutrinos will be emitted copiously during the core-collapse explosion and can help the gravitational wave counterpart search. in this work, we develop a multimessenger strategy to look for such astrophysical objects. we exploit a global network of both low-energy neutrino and gravitational wave detectors. first, we discuss how to improve the detection potential of the neutrino sub-network by exploiting the time profile of a neutrino burst from a core-collapse supernova. we show that in the proposed approach, neutrino detectors can gain at least 10% of detection efficiency at the distance where their efficiency drops. then, we combine the information provided by gravitational wave and neutrino signals in a multimessenger analysis. in particular, by using the clusters of low-energy neutrinos observed by lvd and kamland detectors in combination with the gravitational wave triggers from ligo-virgo detector network, we obtain an increase of the probability to detect the gravitational wave signal from a core-collapse supernova at 60 kpc, from zero to ~33% for some specific gravitational wave emission model. | multimessenger analysis strategy for core-collapse supernova search: gravitational waves and low-energy neutrinos |
direct observations of core-collapse supernovae (sne) and their red supergiant (rsg) progenitors suggest that the upper mass limit of rsgs may be only about 16.5{--}18{m}⊙ , while the standard theoretical value is as much as 25{m}⊙ . we investigate the possibility that rsgs with m\gt 16.5{--}18{m}⊙end their lives as failed supernovae (fsne) and analyze their contribution to the relic supernova neutrino spectrum. we show that adopting this mass limit simultaneously solves both the rsg problem and the supernova rate problem. in addition, energetic neutrinos that originated from fsne are sensitive to the explosion mechanism, and in particular, to the nuclear equation of state (eos). we show that this solution to the rsg problem might also be used to constrain the eos for failed supernovae. | red-supergiant and supernova rate problems: implication for the relic supernova neutrino spectrum |
we study the influence of hot and dense matter in core-collapse supernovae by adopting an up-to-date nuclear equation of state (eos) based on the microscopic nuclear many-body frameworks. we explore effects of the eos based on the dirac-brückner-hartree-fock theory through comparisons with those based on the variational method. we also examine effects of the differences in the composition of nuclei and nucleons by using the same eos as the variational method but employing two different treatments in computations of nuclear abundances. we perform numerical simulations of core-collapse supernovae adopting the three eoss. we also perform numerical simulations of the long-term evolution over 70 s of the proto-neutron star cooling. we show that the impacts of different modeling of the composition are remarkable as in those due to different treatments of uniform matter in the gravitational collapse, bounce and shock propagation. the cooling of a proto-neutron star and the resulting neutrino emission are also affected by the compositional difference even if the same treatment is used in computing uniform matter of the eos. | effects of nuclear matter and composition in core-collapse supernovae and long-term proto-neutron star cooling |
the classical limit on the accretion luminosity of a neutron star is given by the eddington luminosity. the advanced models of accretion on to magnetized neutron stars account for the appearance of magnetically confined accretion columns and allow the accretion luminosity to be higher than the eddington value by a factor of tens. however, the recent discovery of pulsations from ultraluminous x-ray source (ulx) in ngc 5907 demonstrates that the accretion luminosity can exceed the eddington value up to by a factor of 500. we propose a model explaining observational properties of ulx-1 in ngc 5907 without any ad hoc assumptions. we show that the accretion column at extreme luminosity becomes advective. enormous energy release within a small geometrical volume and advection result in very high temperatures at the bottom of accretion column, which demand to account for the energy losses due to neutrino emission which can be even more effective than the radiation energy losses. we show that the total luminosity at the mass accretion rates above 1021 g s-1 is dominated by the neutrino emission similarly to the case of core-collapse supernovae. we argue that the accretion rate measurements based on detected photon luminosity in case of bright ulxs powered by neutron stars can be largely underestimated due to intense neutrino emission. the recently discovered pulsating ulx-1 in galaxy ngc 5907 with photon luminosity of {∼ } 10^{41} {erg s^{-1}} is expected to be even brighter in neutrinos and is thus the first known neutrino pulsar. | ultraluminous x-ray sources as neutrino pulsars |
we show that the spectral split of a neutrino ensemble, which initially consists of electron type neutrinos, is analogous to the bardeen-cooper-schrieffer-bose-einstein condensate (bcs-bec) crossover already observed in ultracold atomic gas experiments. such a neutrino ensemble mimics the deleptonization burst of a core collapse supernova. although these two phenomena belong to very different domains of physics, the propagation of neutrinos from highly interacting inner regions of the supernova to the vacuum is reminiscent of the evolution of cooper pairs between weak and strong interaction regimes during the crossover. the hamiltonians and the corresponding many-body states undergo very similar transformations if one replaces the pair quasispin of the latter with the neutrino isospin of the former. | spectral splits of neutrinos as a bcs-bec crossover type phenomenon |
we study models in which neutrino masses are generated dynamically at cosmologically late times. our study is purely phenomenological and parameterized in terms of three effective parameters characterizing the redshift of mass generation, the width of the transition region, and the present day neutrino mass. we also study the possibility that neutrinos become strongly self-interacting at the time where the mass is generated. we find that in a number of cases, models with large present day neutrino masses are allowed by current cmb, bao and supernova data. the increase in the allowed mass range makes it possible that a non-zero neutrino mass could be measured in direct detection experiments such as katrin. intriguingly we also find that there are allowed models in which neutrinos become strongly self-interacting around the epoch of recombination. | constraining dynamical neutrino mass generation with cosmological data |
we calculate the spin-flavor precession (sfp) of dirac neutrinos induced by strong magnetic fields and finite neutrino magnetic moments in dense matter. as found in the case of majorana neutrinos, the sfp of dirac neutrinos is enhanced by the large magnetic field potential and suppressed by large matter potentials composed of the baryon density and the electron fraction. the sfp is possible irrespective of the large baryon density when the electron fraction is close to 1 /3 . the diagonal neutrino magnetic moments that are prohibited for majorana neutrinos enable the spin precession of dirac neutrinos without any flavor mixing. with supernova hydrodynamics simulation data, we discuss the possibility of the sfp of both dirac and majorana neutrinos in core-collapse supernovae. the sfp of dirac neutrinos occurs at a radius where the electron fraction is 1 /3 . the required magnetic field of the proto-neutron star for the sfp is a few 1014 g at any explosion time. for the majorana neutrinos, the required magnetic field fluctuates from 1013 g to 1015 g . such a fluctuation of the magnetic field is more sensitive to the numerical scheme of the neutrino transport in the supernova simulation. | spin-flavor precession of dirac neutrinos in dense matter and its potential in core-collapse supernovae |
selected results from the multipurpose large volume detector (lvd) are presented. investigations at the lvd setup are being performed according to the program of continuous searches for neutrinos from supernova explosions in the milky way galaxy and muon- and neutron-physics programs. at the present time, the lvd setup is the largest scintillation detector, which possesses a unique potential for studies in the realms of underground physics. | lvd—multipurpose russian-italian detector |
we analyze the effect of the antineutrino mass over the β--decay rates calculated within the scheme of the gross theory of beta decay (gtbd). we give a non-null value to the mass of the antineutrino participating in β--decay, (a ,z )→(a ,z +1 )+e-+ν¯ e, which is usually neglected because we know it is small compared with electron mass. we have slightly modified the gtdb by inserting the antineutrino mass in the formalism. we have adopted a gaussian energy distribution function with the axial-vector weak coupling constant ga = 1, as well as a new set of the adjustable parameter σn related to the standard deviation for the gamow-teller resonance, updated experimental mass defects, and also an improved approximation for the fermi function. our sample consists of a set of 94 nuclei of interest in the pre-supernova phase, which have experimental data in terrestrial conditions available in the letter of nuclide. we have compared the calculation without the inclusion of the antineutrino mass with that adopting a really overestimated value of 50 kev for it to illustrate the effect on the decay rates. we have shown that they are improved only by approximately one per thousand in this case. we conclude that the effect of the antineutrino mass on decay rates is not relevant. | effects of antineutrino mass on β--decay rates calculated within the gross theory of beta decay |
entanglement of constituents of a many-body system is a recurrent feature of quantum behaviour. quantum information science provides tools, such as the entanglement entropy, to help assess the amount of entanglement in such systems. many-neutrino systems are present in core-collapse supernovae, neutron star mergers, and the early universe. recent work in applying the tools of quantum information science to the description of the entanglement in astrophysical many-neutrino systems is reviewed. | quantum entanglement and neutrino many-body systems |
we make extensive numerical studies of masses and radii of proto-neutron stars during the first second after their birth in core-collapse supernova events. we use a quasi-static approach for the computation of proto-neutron star structure, built on parametrized entropy and electron fraction profiles, that are then evolved with neutrino cooling processes. we vary the equation of state of nuclear matter, the proto-neutron star mass, and the parameters of the initial profiles, to take into account our ignorance of the supernova progenitor properties. our results suggest that if masses and radii of a proto-neutron star can be determined in the first second after the birth, e.g. from gravitational wave emission, no information could be obtained on the corresponding cold neutron star and therefore on the cold nuclear equation of state. similarly, it seems unlikely that any property of the proto-neutron star equation of state (hot and not beta-equilibrated) could be determined either, mostly due to the lack of information on the entropy, or equivalently temperature, distribution in such objects. | what can be learned from a proto-neutron star's mass and radius? |
we present the first fully relativistic numerical calculations of differentially rotating strange quark stars models for broad ranges of the maximum density and of the degree of differential rotation. our simulations are performed with the very accurate and stable multi-domain spectral code flatstar and use the mit bag model for describing strange quark matter. our calculations, based on a thorough exploration of the solution space, show that the maximum mass of strange stars depends on both the degree of differential rotation and a type of solution, similar to neutron stars. the highest increase of the maximum mass (compared to the value for a non-rotating star) is obtained for models with a low degree of differential rotation. this highest mass is over four times larger than that of the equivalent non-rotating configuration. comparing our results with calculations done for realistic models of neutron stars, we conclude that for small degrees of differential rotation, strange stars can sustain masses much larger than stars made from nuclear matter, which reinforces the hope of demonstrating, or of ruling out, the existence of strange matter through observation of the gravitational waves, gamma-rays, or neutrinos of the massive material object born from the merger of a compact binary system or during some supernova events. | maximum mass of differentially rotating strange quark stars |
we compute with lattice field theory the vector and axial static structure factors of the unitary gas for arbitrary temperature above the superfluid transition and for fugacities 0.1 <z <1.0 . using the lattice formulation, we calculate beyond the validity of the virial expansion, a commonly used technique in many-body physics. we find qualitative differences in the behavior of the structure factors at high fugacity compared to the predictions of the virial expansion. due to the large scattering length of neutrons, we expect the unitary gas structure factors to approximate the structure factors of hot neutron gases, and we therefore expect our calculations to be useful in supernova simulations, where neutron gas structure factors are needed to compute in-medium neutrino-neutron scattering rates. | structure factors of the unitary gas under supernova conditions |
a new theoretical framework, based on the quantum field theory of open systems applied to neutrinos, has been developed to describe the neutrino evolution in external environments accounting for the effect of the neutrino quantum decoherence. the developed new approach enables one to obtain the explicit expressions of the decoherence and relaxation parameters that account for a particular process, in which the neutrino participates, and also for the characteristics of an external environment and of the neutrino itself, including the neutrino energy. we have used this approach to consider a new mechanism of the neutrino quantum decoherence engendered by the neutrino radiative decay to photons and dark photons in an astrophysical environment. the importance of the performed studies is highlighted by the prospects of the forthcoming new large volume neutrino detectors that will provide new frontier in high-statistics measurements of neutrino fluxes from supernovae. | neutrino quantum decoherence engendered by neutrino radiative decay |
the titus, tokai intermediate tank for unoscillated spectrum, detector, is a proposed gd-doped water cherenkov tank with a magnetised muon range detector downstream. it is located at j-parc at about 2 km from the neutrino target and it is proposed as a potential near detector for the hyper-kamiokande experiment. assuming a beam power of 1.3 mw and 27.05 x 10^{21} protons-on-target the sensitivity to cp and mixing parameters achieved by hyper-kamiokande with titus as a near detector is presented. also, the potential of the detector for cross sections and standard model parameter determination, supernova neutrino and dark matter are shown. | titus: the tokai intermediate tank for the unoscillated spectrum |
the evolution of many astrophysical systems is dominated by the interaction between matter and radiation such as photons or neutrinos. the dynamics can be described by the evolution equations of radiation hydrodynamics in which reactions between matter particles and radiation quanta couples the hydrodynamic equations to those of radiative transfer, see munier & weaver (1986a), munier & weaver (1986b).. the numerical treatment has to account for their potential stiffness (e.g., in optically thick environments). in this article, we will present a new method to numerically integrate these equations in a stable way by using minimally implicit runge-kutta methods. with these methods, the inversion of the implicit operator can be done analytically. we also take into account the physical behavior of the evolved variables in the limit of the stiff regime. we will show the results of applying this method to the reactions between neutrinos and matter in core-collapse supernovae simulations. | minimally implicit methods for the numerical integration of the neutrino transport equations |
the progenitor stars of core-collapse supernovae (ccsne) are asymmetrically fluctuating due to turbulent convections in the late stages of their lives. the progenitor asymmetry at the pre-supernova stage has recently caught the attention as a new ingredient to facilitate shock revival in the delayed neutrino-heating mechanism. in this paper, we investigate the importance of the progenitor asymmetries to shock revival with a semi-analytical approach. free parameters were chosen such that the time evolution of shock radii and mass accretion rates are compatible with the results of detailed numerical simulations of ccsne in spherical symmetry. we first estimate the amplitude of asymmetries required for the shock revival by the impulsive change of pre-shock flows in the context of neutrino-heating mechanism, and then convert the amplitude to the corresponding amplitude in the pre-supernova phase by taking into account the growth of asymmetries during infall. we apply our model to various types of progenitors and find that the requisite amplitude of pre-supernova asymmetry is roughly three times larger than the prediction by current stellar evolution models unless other additional physical ingredients such as multidimensional fluid instabilities and turbulent convections in post-shock flows aid shock revival. we thus conclude that progenitor asymmetries cannot trigger the shock revival by the impulsive way but rather play a supplementary role in reality. | on the importance of progenitor asymmetry to shock revival in core-collapse supernovae |
i estimate the frequencies of gravitational waves from jittering jets that explode core collapse supernovae (ccsne) to crudely be 5-30 hz, and with strains that might allow detection of galactic ccsne. the jittering jets explosion mechanism (jjem) asserts that most ccsne are exploded by jittering jets that the newly born neutron star (ns) launches within a few seconds. according to the jjem, instabilities in the accreted gas lead to the formation of intermittent accretion disks that launch the jittering jets. earlier studies that did not include jets calculated the gravitational frequencies that instabilities around the ns emit to have a peak in the crude frequency range of 100-2000 hz. based on a recent study, i take the source of the gravitational waves of jittering jets to be the turbulent bubbles (cocoons) that the jets inflate as they interact with the outer layers of the core of the star at thousands of kilometers from the ns. the lower frequencies and larger strains than those of gravitational waves from instabilities in ccsne allow future, and maybe present, detectors to identify the gravitational wave signals of jittering jets. detection of gravitational waves from local ccsne might distinguish between the neutrino-driven explosion mechanism and the jjem. | predicting gravitational waves from jittering-jets-driven core collapse supernovae |
the roles of neutrinos and convective instability in collapsing supernovae are considered. spherically symmetrical computations of the collapse using the boltzmann equation for the neutrinos lead to the formation of the condition of convective instability, {( {{partial p}/{partial s}} )_{ρ {y_l}}}{ds}/{dr} + {( {{partial p}/{partial {y_l}}} )_{ρ s}}{d{y_l}}/{dr} < 0, in a narrow region of matter accretion above the neutrinosphere. if instability arises in this region, the three-dimensional solution will represent a correction to the spherically symmetrical solution for the gravitational collapse. the mean neutrino energies change only negligibly in the narrow region of accretion. nuclear statistical equilibrium is usually assumed in the hot proto-neutron stellar core, to simplify the computations of the collapse. neutronization with the participation of free neutrons is most efficient. however, the decay of nuclei into nucleons is hindered during the collapse, because the density grows too rapidly compared to the growth in the temperature, and an appreciable fraction of the energy is carried away by neutrinos. the entropy of the matter per nucleon is modest at the stellar center. all the energy is in degenerate electrons during the collapse. if the large energy of these degenerate electrons is taken into account, neutrons are efficiently formed, even in cool matter with reduced ye(the difference between the numbers of electrons and positrons per nucleon). this process brings about an increase in the optical depth to neutrinos, the appearance of free neutrons, and an increase in the entropy per nucleon at the center. the convectively unstable region at the center increases. the development of large-scale convection is illustrated using a multi-dimensional gas-dynamical model for the evolution of a stationary, unstable state (without taking into account neutrino transport). the time for the development of convective instability (several milliseconds) does not exceed the time for the existence of the unstable region at the center (10ms). the realization of this type of instability is fundamentally different from a spherically symmetrical model. the flux of neutrinos changes and the mean energy of the neutrinos is increased, which has important implications for the detection of neutrinos from supernovae. for these same reasons, the energy absorped in the supernova envelope also changes in the transition to such a multi-dimensional model. | neutronization of matter in a stellar core and convection during gravitational collapse |
neutrino nuclear scattering in hot and dense matter relevant for supernovae, neutron star mergers, and proto-neutron stars is considered. at finite temperature, neutrinos exhibit exo- and endoenergetic scattering on nuclear species due to the neutral-current gamow-teller interaction component. from an analysis of energy transfer and straggling cross sections we demonstrate that additional noticeable mechanisms in equilibrating neutrinos with matter originate in magnetized nucleon gas. average energy transfer, i.e., ratio of energy transfer and scattering cross sections, depends almost linearly on neutrino energy and changes from positive to negative value. for hot nuclear material such crossover between acceleration and stopping regimes occurs when neutrino energy is about a factor four of temperature. similar features are displayed for neutrino scattering on hot atomic nuclei. for the 56fe nucleus the stopping regime starts at energies slightly above than four times temperature. possible effects in neutrino transport and spectra are discussed. | energy exchange in neutrino nuclear scattering |
we calculate the differential scattering rate for thermal neutrinos in a hot and dilute gas of interacting neutrons using linear response theory. the dynamical structure factors for density and spin fluctuations of the strongly interacting neutron matter, expected in the neutrino decoupling regions of supernovae and neutron star mergers, are calculated in the virial expansion for the first time. correlations due to nucleon-nucleon interactions are taken into account using a pseudopotential that reproduces measured nucleon-nucleon phase shifts, and we find that attractive s -wave interactions enhance the density response and suppress the spin response of neutron matter. the net effect of neutron correlations is to strongly suppress backscattering. moreover, we find nearly exact scaling laws for the response functions, valid for the range t =5 -10 mev and q <30 mev, allowing us to obtain analytic results for the dynamic structure factors at second order in the fugacity of the neutron gas. we find that the modification of scattering rates depends on the energy and momentum exchanged. the use of dynamical structure factors can lead to corrections of the scattering rate at the 10-20% level compared to approximations based on static structure factors. | neutrino-nucleon scattering in the neutrino-sphere |
we assess the utility of an optimization-based data assimilation (d.a.) technique for treating the problem of nonlinear neutrino flavor transformation in core-collapse supernovae. d.a. uses measurements obtained from a physical system to estimate the state variable evolution and parameter values of the associated model. formulated as an optimization procedure, d.a. can offer an integration-blind approach to predicting model evolution, which offers an advantage for models that thwart solution via traditional numerical integration techniques. further, d.a. performs most optimally for models whose equations of motion are nonlinearly coupled. in this exploratory work, we consider a simple steady-state model with two monoenergetic neutrino beams coherently interacting with each other and a background medium. as this model can be solved via numerical integration, we have an independent consistency check for d.a. solutions. we find that the procedure can capture key features of flavor evolution over the entire trajectory, even given measurements of neutrino flavor only at the endpoint, and with an assumed known initial flavor distribution. further, the procedure permits an examination of the sensitivity of flavor evolution to estimates of unknown model parameters, locates degeneracies in parameter space, and can identify the specific measurements required to break those degeneracies. | an optimization-based approach to calculating neutrino flavor evolution |
a search is performed for supernovalike neutrino interactions coincident with 76 gravitational wave events detected by the ligo/virgo collaboration. for 40 of these events, full readout of the time around the gravitational wave is available from the nova far detector. for these events, we set limits on the fluence of the sum of all neutrino flavors of f <7 (4 )×1010 cm-2 at 90% c.l. assuming energy and time distributions corresponding to the garching supernova models with masses 9.6 (27 ) m⊙ . under the hypothesis that any given gravitational wave event was caused by a supernova, this corresponds to a distance of r >29 (50 ) kpc at 90% c.l. weaker limits are set for other gravitational wave events with partial far detector data and/or near detector data. | extended search for supernovalike neutrinos in nova coincident with ligo/virgo detections |
based on the kompaneets approximation, we develop a robust methodology to calculate spectral redistribution via inelastic neutrino-nucleon scattering in the context of core-collapse supernova simulations. the resulting equations conserve lepton number to machine precision and scale linearly, not quadratically, with number of energy groups. the formalism also provides an elegant means to derive the rate of energy transfer to matter which, as it must, automatically goes to zero when the neutrino radiation field is in thermal equilibrium. furthermore, we derive the next higher order in ɛ /m c2 correction to the neutrino kompaneets equation. unlike other kompaneets schema, ours also generalizes to the case of anisotropic angular distributions, while retaining the conservative form that is a hallmark of the classical kompaneets equation. our formalism enables immediate incorporation into supernova codes that follow the spectral angular moments of the neutrino radiation fields. | generalized kompaneets formalism for inelastic neutrino-nucleon scattering in supernova simulations |
gamma-ray bursts (grbs) might be powered by black hole (bh) hyperaccretion systems via the blandford-znajek (bz) mechanism or neutrino annihilation from neutrino-dominated accretion flows (ndafs). magnetic coupling (mc) between the inner disc and bh can transfer angular momentum and energy from the fast-rotating bh to the disc. the neutrino luminosity and neutrino annihilation luminosity are both efficiently enhanced by the mc process. in this paper, we study the structure, luminosity, mev neutrinos, and gravitational waves (gws) of magnetized ndafs (mndafs) under the assumption that both the bz and mc mechanisms are present. the results indict that the bz mechanism will compete with the neutrino annihilation luminosity to trigger jets under the different partitions of the two magnetic mechanisms. the typical neutrino luminosity and annihilation luminosity of mndafs are definitely higher than those of ndafs. the typical peak energy of neutrino spectra of mndafs is higher than that of ndafs, but similar to those of core-collapse supernovae. moreover, if the mc process is dominant, then the gws originating from the anisotropic neutrino emission will be stronger particularly for discs with high accretion rates. | neutrinos and gravitational waves from magnetized neutrino-dominated accretion discs with magnetic coupling |
in this study, we present the first multidimensional core-collapse supernovae (ccsne) simulations including qcd axions in order to assess the impact on the ccsn explosion mechanism. we include axions in our simulations through the nucleon-nucleon bremsstrahlung emission channel and as a pure energy-sink term under the assumption that the axions free-stream after being emitted. we perform both spherically symmetric (1d) and axisymmetric (2d) simulations. in 1d, we utilize a parametrized heating scheme to achieve explosions, whereas in 2d we self-consistently realize explosions through the neutrino heating mechanism. our 2d results for a 20 m⊙ progenitor show an impact of the axion emission on the shock behavior and the explosion time when considering values of the pecceiquinn energy scale fa≤2 ×108 gev . the strong cooling due to the axion emission accelerates the contraction of the core and leads to more efficient neutrino heating and earlier explosions. for the axion emission formalism utilized, the values of fa that impact the explosion are close to, but in tension with current limits based on the neutrinos detected from sn 1987a. however, given the nonlinear behavior of the emission and the multidimensional nature of ccsne,we suggest that a self-consistent, multidimensional approach to simulating ccsne, including any late time accretion and cooling, is needed to fully explore the axion bounds from supernovae and the impact on the ccsn explosion mechanism. | neutrino driven explosions aided by axion cooling in multidimensional simulations of core-collapse supernovae |
the influence of propagation dynamics of intense neutrino beams on the hydrodynamic jeans instability in a magnetized quantum plasma is investigated. the dynamics of a self-gravitating, magnetized electron-ion quantum plasma weakly interacting with neutrinos are considered in a neutrino magnetohydrodynamic model. the modified dispersion relations of jeans instability and fast neutrino-driven short wavelength instability are established using a linear perturbation method. in oblique propagation, the jeans instability condition is modified due to the presence of neutrino beam effects, whereas no effect was observed in parallel and perpendicular propagations. the neutrino beam density stabilizes, while the free energy of the neutrino beam destabilizes the growth rate of jeans instability. the estimated jeans time scale is comparable to the time scale of supernova explosion. the time scale of neutrino beam instability is much shorter than the jeans time scale which results in faster neutrino mixing in the gravitational collapse of the system. the consequences of neutrino beam interactions with a magnetized, self-gravitating quantum plasma have been addressed in astrophysical environments. | influence of neutrino beam on the jeans instability in a magnetized quantum plasma |
the helium and lead observatory (halo) is a new supernova neutrino detector at snolab base on neutrino reactions on lead. currently it is the only detector whose signal is dominated by the νe component of supernova neutrinos. a short description of the detector and its current status are given. | halo, a supernova neutrino observatory |
during the accretion phase of a core-collapse supernovae, large amplitude turbulence is generated by the combination of the standing accretion shock instability and convection driven by neutrino heating. the turbulence directly affects the dynamics of the explosion, but there is also the possibility of an additional, indirect, feedback mechanism due to the effect turbulence can have upon neutrino flavor evolution and thus the neutrino heating. in this paper we consider the effect of turbulence during the accretion phase upon neutrino evolution, both numerically and analytically. adopting representative supernova profiles taken from the accretion phase of a supernova simulation, we find the numerical calculations exhibit no effect from turbulence. we explain this absence using two analytic descriptions: the stimulated transition model and the distorted phase effect model. in the stimulated transition model turbulence effects depend upon six different lengthscales, and three criteria must be satisfied between them if one is to observe a change in the flavor evolution due to stimulated transition. we further demonstrate that the distorted phase effect depends upon the presence of multiple semi-adiabatic msw resonances or discontinuities that also can be expressed as a relationship between three of the same lengthscales. when we examine the supernova profiles used in the numerical calculations we find the three stimulated transition criteria cannot be satisfied, independent of the form of the turbulence power spectrum, and that the same supernova profiles lack the multiple semi-adiabatic msw resonances or discontinuities necessary to produce a distorted phase effect. thus, we conclude that even though large amplitude turbulence is present in supernova during the accretion phase, it has no effect upon neutrino flavor evolution. this article belongs to the focus on microphysics in core-collapse supernovae: 30 years since sn1987a special issue. | the effect of core-collapse supernova accretion phase turbulence on neutrino flavor evolution |
neutrino emission and their transport of energy to the supernova shock region are sensitive to the physics of hot and dense nuclear matter, which is a complex problem due to the strong correlations induced by nuclear forces. we derive charged-current opacities for electron neutrinos and antineutrinos in supernova matter using a self-consistent approach based on the skyrme effective interaction. we include a mean field energy shift due to nuclear interaction and corrections due to rpa correlations. a complete treatment of the full skyrme interaction, including a spin-orbit term, is given. to test the effect of rpa corrections, neutrino and antineutrino opacities are computed using different skyrme parameterisations consistent with a number of infinite matter constraints. | skyrme-rpa study of charged-current neutrino opacity in hot and dense supernova matter |
using the thermal quasiparticle random-phase approximation, we study the process of neutrino and antineutrino capture on hot nuclei in supernova environments. for the sample nuclei 56fe and 82ge we perform a detailed analysis of thermal effects on the strength distribution of allowed gamow-teller (gt) transitions which dominate low-energy charged-current neutrino reactions. the finite-temperature cross sections are calculated taking into account the contributions of both allowed and forbidden transitions. the enhancement of the low-energy cross sections is explained by considering thermal effects on the gt± strength. for 56fe we compare the calculated finite-temperature cross sections with those obtained from large-scale shell-model calculations. | neutrino absorption by hot nuclei in supernova environments |
the recent study of the sn 2013fs flash spectrum suggests an enormous explosion energy for sne iip, far beyond the possibilities of the neutrino mechanism. the issue of the explosion energy of sn 2013fs is revisited, making use of the effects of the early supernova interaction with the dense circumstellar shell. the velocity of the cold dense shell between reverse and forward shocks is inferred from the analysis of the broad he ii 4686 å on day 2.4. this velocity, alongside other observables, provides us with an alternative energy estimate of ∼1.8 × 1051 erg for the preferred mass of ∼10 m⊙. the inferred value is within the range of neutrino-driven explosions. | the explosion energy of the type iip supernova sn 2013fs with a confined dense circumstellar shell |
icecube is a cubic kilometer neutrino detector array in the antarctic ice that was designed to search for astrophysical, high-energy neutrinos. it has detected a diffuse flux of astrophysical neutrinos that appears to be of extragalactic origin. a possible contribution to this diffuse flux could stem from core-collapse supernovae. the high-energy neutrinos could either come from the interaction of the ejecta with a dense circumstellar medium or a jet, emanating from the star's core, that stalls in the star's envelope. here, we will present results of a stacking analysis to search for this high-energy neutrino emission from core-collapse supernovae using 7 years of $\nu_\mu$ track events from icecube. | searching for high-energy neutrinos from core-collapse supernovae with icecube |
we investigate the quark deconfinement phase transition in cold (t = 0) and hot β-stable hadronic matter. assuming a first-order phase transition, we calculate and compare the nucleation rate and the nucleation time due to quantum and thermal nucleation mechanisms. we show that above a threshold value of the central pressure a pure hadronic star (hs) (i.e. a compact star with no fraction of deconfined quark matter (qm)) is metastable to the conversion to a quark star (qs) (i.e. a hybrid star or a strange star). this process liberates a huge amount of energy, of the order of 1053 erg, which produces a powerful neutrino burst, likely accompanied by intense gravitational waves emission, and possibly by a second delayed (with respect to the supernova explosion forming the hs) explosion which could be the energy source of a powerful gamma-ray burst (grb). this stellar conversion process populates the qs branch of compact stars, thus one has in the universe two coexisting families of compact stars: hss and qss. we introduce the concept of critical mass mcr for cold hss and proto-hadronic stars (phss), and the concept of limiting conversion temperature for phss. we show that phss with a mass m < mcr could survive the early stages of their evolution without decaying to qss. finally, we discuss the possible evolutionary paths of phss. | quark deconfinement in neutron stars and astrophysical implications |
using the data from the online fast processing chain, the km3net collaboration has performed a dedicated search for track-like muon neutrino events arriving from the direction of grb 221009a (dichiara et al. gcn 32632 (swift); veres et al. gcn 32636 (fermi-gbm)). the search covers the time range of [t0-50s, t0+5000s], with t0 being the trigger time reported by fermi-gbm (t0=2022-10-09 13:16:59.00 utc), during which both km3net detectors were collecting good quality data. however, the grb location was above the km3net horizon (mean elevation of about ~40deg) during the search time window, significantly reducing the point-like source sensitivity. in both detectors, zero events were observed in the search window, while o(0.1) were expected from the background. the online fast processing uses preliminary calibrations and detector alignment, which will be superseded in a future elaborated analysis. a parallel search has been performed in the mev range (eur.phys.j.c 82 (2022) 4, 317) without any significant neutrino coincidence. km3net is a large undersea (mediterranean sea) infrastructure hosting two neutrino detectors, sensitive to burst of supernova neutrinos in the mev range and to astrophysical neutrinos in the gev-pev energy range: arca at high energy and orca at low energy. a total of 21 and 11 detection lines are currently in operation in arca and orca, respectively. | grb 221009a: search for neutrinos with km3net |
the neutrino burst detected during supernova sn 1987a is explained in a strangeon star model, in which it is proposed that a pulsar-like compact object is composed of strangeons (strangeon: an abbreviation for “strange nucleon”). a nascent strangeon star’s initial internal energy is calculated, with the inclusion of pion excitation (energy around 1053 erg, comparable to the gravitational binding energy of a collapsed core). a liquid-solid phase transition at temperature ∼ 1-2 mev may occur only a few tens of seconds after core collapse, and the thermal evolution of a strangeon star is then modeled. it is found that the neutrino burst observed from sn 1987a can be reproduced in such a cooling model. | supernova neutrinos in a strangeon star model |
according to conventional wisdom the 5 h early mont blanc burst probably was not associated with sn 1987a, but if it was genuine, some exotic physics explanation had to be responsible. here we consider one truly exotic explanation, namely faster-than-light neutrinos having mν2 = - 0.38 kev2. it is shown that the mont blanc burst is consistent with the distinctive signature of that explanation i.e., an 8 mev antineutrino line from sn 1987a. it is further shown that a model of core collapse supernovae involving dark matter particles of mass 8 mev would in fact yield an 8 mev antineutrino line. moreover, that dark matter model predicts 8 mev ν ,νbar and e+e- pairs from the galactic center, a place where one would expect large amounts of dark matter to collect. the resulting e+ would create γ - rays from the galactic center, and a fit to mev γ - ray data yields the model's dark matter mass, as well as the calculated source temperature and angular size. these good fits give indirect experimental support for the existence of an 8 mev antineutrino line from sn 1987a. more direct support comes from the spectrum of n ∼ 1000 events recorded by the kamiokande-ii detector on the day of sn 1987a, which appear to show an 8 mev line atop the detector background. this νbar line, if genuine, has been well-hidden for 30 years because it occurs very close to the peak of the background. this fact might ordinarily justify extreme skepticism. in the present case, however, a more positive view is called for based on (a) the very high statistical significance of the result (30σ), (b) the use of a detector background independent of the sn 1987a data using a later k-ii data set, and (c) the observation of an excess above the background spectrum whose central energy and width both agree with that of an 8 mev νbar line broadened by 25% resolution. most importantly, the last observation is in accord with the prior prediction of an 8 mev νbar line based on the mont blanc data, and the dark matter model, itself supported by experimental observations. lastly, it is noted that the tachyonic interpretation of the mont blanc burst fits the author's earlier unconventional 3 + 3 model of the neutrino mass states. experimental corroboration should be sought for the linked hypotheses of an 8 mev νbar line or an mν2 = - 0.38 kev2. the former might be seen in existing astrophysical data, while the latter should be proven or refuted by the katrin experiment in a short data-taking period. | the mont blanc neutrinos from sn 1987a: could they have been monochromatic (8 mev) tachyons with m2 = - 0.38 kev2? |
background: inelastic neutrino-nucleus scattering is important for understanding core-collapse supernovae and the detection of emitted neutrinos from such events in earth-based detectors. direct measurement of the cross sections is difficult and has only been performed on a few nuclei. it is, therefore, important to develop indirect techniques from which the inelastic neutrino-nucleus scattering cross sections can be determined. purpose: this paper presents a development of the (6li,*6li[t =1 ,tz=0 ,0+,3.56 mev ] ) reaction at 100 mev/u as a probe for isolating the isovector spin-transfer response in the inelastic channel (δ s =1 ,δ t =1 ,δ tz=0 ) from which the gamow-teller transition strengths from nuclei of relevance for inelastic neutrino-nucleus scattering cross sections can be extracted. method: by measuring the 6li ejectile in a magnetic spectrometer and selecting events in which the 3.56 mev γ ray from the decay of the *6li[3.56 mev ] state is detected, the isovector spin-transfer selectivity is obtained. high-purity germanium clover detectors served to detect the γ rays. doppler reconstruction was used to determine the γ energy in the rest frame of 6li. from the 6li and 3.56 mev γ -momentum vectors the excitation energy of the residual nucleus was determined. results: in the study of the 12c(6li,*6li[3.56 mev ]) reaction, the isovector spin-transfer excitation-energy spectrum in the inelastic channel was successfully measured. the strong gamow-teller state in 12c at 15.1 mev was observed. comparisons with the analog 12c(6li,6he) reaction validate the method of extracting the gamow-teller strength. in measurements of the 24mg,93nb(6li,*6li[3.56 mev ]) reactions, the 3.56 mev γ peak could not be isolated from the strong background in the γ spectrum from the decay of the isoscalar excitations. it is argued that by using a γ -ray tracking array instead of a clover array, it is feasible to extend the mass range over which the (6li,*6li) reaction can be used for extracting the isovector spin-transfer response up to mass numbers of ∼25 and perhaps higher. conclusions: it is demonstrated that the (6li,*6li[3.56 mev ]) reaction probe can be used to isolate the inelastic isovector spin-transfer response in nuclei. application to nuclei with mass numbers of about 25 or more, however, will require a more efficient γ -ray array with a better tracking capability. | the (6li,*6li[3.56 mev ] ) reaction at 100 mev/u as a probe of gamow-teller transition strengths in the inelastic scattering channel |
neutrinos from core collapse supernovae can excite nuclei of some detector materials beyond their neutron emission thresholds. detection of these neutrons can give valuable information about the supernova explosion mechanism and possibly also throw light on neutrino properties. in this article, we give a brief review of the basic physics of neutrino-induced neutron emission and describe the results of some recent calculations of supernova neutrino-induced neutrons for some specific target detector materials due to charged current (cc) interactions of the electron flavored neutrinos and antineutrinos as well as due to neutral current (nc) interactions of neutrinos and antineutrinos of all flavors with the detector nuclei. we highlight the fact that a detector material such as lead with a relatively large neutron excess produces neutrons dominantly through the cc interaction of the νes, whereas a material such as iron with small neutron excess produces neutrons dominantly through the combined nc interaction of all the six neutrino and antineutrino species. this raises the interesting possibility of probing the fraction of mu- and tau-flavored neutrinos (which interact only through nc interaction) in the supernova neutrino flux by means of simultaneous detection of a supernova in a lead and an iron detector, for example. | supernova neutrino detection through neutron emission by nuclei |
based on the shell and pair effects and the decay energy, we investigate the comparative half‑lives of β−‑decay for some iron group nuclei and mainly discuss the electron energy, beta decay threshold energy, and the antineutrino energy losses by β−‑decay of several typical iron isotopes in the presence of strong electron screening (ses) and in the framework of linear response theory. our main findings include the following: (a) antineutrino energy losses increase greatly by the ses, and the screening enhancement factor can reach 1,018 due to the q‑value correction and shell and pairing effects in the case of ses; (b) the antineutrino energy loss rates can be suppressed at a relatively lower density and in a higher temperature environment (e.g., 0.1 < ρ7 < 900, t9 > 30); and (c) the screening enhancement factor can be decreased by about 16.62% (e.g., for 56co). | supernova antineutrino energy losses of 59co, 56co, 56ni, and 56fe by β--decay in strongly screened plasma |
we demonstrate that the neutrino-driven outflows inside exploding core-collapse supernovae possess a special property of near-criticality, that is, they are on the edge of forming termination shocks. we derive a novel criterion for the formation of the shock, in terms of the fundamental parameters of the problem: the neutrino luminosity and energy as well as the properties of the protoneutron star. the criterion provides a unified description of the available numerical results and motivates future simulations. the property of near-criticality makes the neutrino signatures of the termination shocks a sensitive diagnostic of the physical conditions around the pns several seconds into the explosion. the expected signal at dune is found to be statistically significant. | near-critical supernova outflows and their neutrino signatures |
in this work we present computed cross sections for the incoherent neutral-current neutrino scattering off the stable cadmium isotopes. the main focus is on supernova neutrinos. the nuclear states of the even-mass and odd-mass cadmium isotopes have been constructed using the quasiparticle random-phase approximation and the microscopic quasiparticle-phonon model, respectively. the computed cross sections are folded with suitably parametrized fermi-dirac distributions of the supernova (anti)neutrinos energies to obtain realistic estimates of the nuclear responses to these neutrinos. | neutrino scattering off the stable cadmium isotopes: neutral-current processes |
the centers of the core-collapse supernovae are one of the densest environments in the universe. under such conditions, it is conceivable that a first-order phase transition from ordinary nuclear matter to the quark-gluon plasma occurs. this transition releases a large amount of latent heat that can drive a supernova explosion and may imprint a sharp signature in the neutrino signal. we show how this snap feature, if observed at large-scale neutrino detectors, can set competitive limits on the neutrino masses and assist the localization of the supernova via triangulation. the 95% c.l. limit on the neutrino mass can reach 0.16 ev in ice-cube, 0.22 ev in hyper-kamiokande, and 0.58 ev in dune, for a supernova at a distance of 10 kpc. for the same distance and in the most optimistic neutrino conversion case, the triangulation method can constrain the 1 σ angular uncertainty of the supernova localization within ∼0.3 °- 9.0 ° in the considered pairs of the detectors, leading to an improvement up to an order of magnitude with respect to the often considered in the literature rise time of the neutronization burst. | exploiting stellar explosion induced by the qcd phase transition in large-scale neutrino detectors |
the integral parameters (mass, radius) of hot proto-quark stars that are formed in supernova explosion are studied. we use the mit bag model to determine the pressure of up-down and strage quark matter at finite temperature and in the regime where neutrinos are trapped. it is shown that such stars are heated to temperatures of the order of tens of mev. the maximum possible values of the central temperatures of these stars are determined. it is shown that the energy of neutrinos that are emitted from proto-quark stars is of the order of 250÷300 mev. once formed, the proto-quark stars cool by neutrino emission, which leads to a decrease in the mass of these stars by about 0.16–0.25 m⊙ for stars with the rest masses that are in the range mb=1.22‑1.62 m⊙. | reduction of the mass of the proto-quark star during cooling |
in this study, we investigate the ion-ball screening model (model (i)), focused on the screening electrostatic potential per electron under the wigner-seitz approximation and the q-value correction. by considering the changes of the coulomb free energy and the effects of strong electron screening (ses) on the q-value and the coulomb chemical potential, we discuss the linear-response screening model (model (ii)). we also analyze the influence of the ses on the beta(-) decay antineutrino energy loss rate by considering the corrections of the q-value, the electron chemical potential, and electron energy, as well as the shell and pair effects. the antineutrino energy loss rate is found to increase by two orders of magnitude (e.g., the ses enhancement factor reaches 651.9 for model (ii)) due to the ses effect. | strongly screening β- decay antineutrino energy loss in presupernova |
we study the ratio of neutrino-proton elastic scattering to inverse beta decay event counts, measurable in a scintillation detector like juno, as a key observable for identifying the explosion mechanism of a galactic core-collapse supernova. if the supernova is not powered by the core but rather, e.g., by collapse-induced thermonuclear explosion, then a prolonged period of accretion-dominated neutrino luminosity is predicted. using 1d numerical simulations, we show that the distinct resulting flavor composition of the neutrino burst can be tested in juno with high significance, overcoming theoretical uncertainties in the progenitor star profile and equation of state. | neutrino flavor as a test of the explosion mechanism of core-collapse supernovae |
providing an early warning of galactic supernova explosions from neutrino signals is important in studying supernova dynamics and neutrino physics. a dedicated supernova trigger system has been designed and installed in the data acquisition system at daya bay and integrated into the worldwide supernova early warning system (snews). daya bay's unique feature of eight identically-designed detectors deployed in three separate experimental halls makes the trigger system naturally robust against cosmogenic backgrounds, enabling a prompt analysis of online triggers and a tight control of the false-alert rate. the trigger system is estimated to be fully sensitive to 1987a-type supernova bursts throughout most of the milky way. the significant gain in sensitivity of the eight-detector configuration over a mass-equivalent single detector is also estimated. the experience of this online trigger system is applicable to future projects with spatially distributed detectors. | design, characterization, and sensitivity of the supernova trigger system at daya bay |
we overview the progress of the tables of the equation of state for astrophysical simulations and the numerical methods of neutrino transfer. hot and dense matter play essential roles in core-collapse supernovae and neutron stars. equation of state determines the structure of compact objects and their dynamics through its behavior of thermodynamic quantities. in addition, neutrinos are trapped in supernova cores and neutron star mergers and frequently interact with matter to crucially affect dynamics in determining the explosion mechanism and the final form of compact objects. therefore, it is essential to implement detailed processes of nuclear and neutrino physics in numerical simulations by having reliable data set of the equation of state and reaction rates. we show examples of developments of the equation of state and the neutrino transfer and discuss research directions toward understanding the explosive phenomena by the first principle calculation. | equation of state and neutrino transfer in supernovae and neutron stars |
a large fraction of the energy released during the gravitational collapse of the core of a massive star is carried by neutrinos. neutrinos play the main role in explaining core-collapse supernovae. a self-consistent formulation of the gravitational collapse is solved using multidimensional gas dynamics, taking into account the spectral transport of neutrinos in the framework of neutrino diffusion with diffusion the fluxes limiters. large scale convection leads to an increase in the mean energy of the neutrinos up to 15 mev in compare with the spherically-symmetric case, which is important for explaining supernovae. additionally we considered the collapse in the 3d case with the neutrino transport without the spectrum to specify the role of the modest rotation in the formation of the large scale convection. | large-scale instability in supernovae and the neutrino spectrum |
a large fraction of the energy released during the gravitational collapse of the core of a massive star is carried by neutrinos. neutrinos play the main role in explaining core-collapse supernovae. a self-consistent formulation of the gravitational collapse is solved using 2d gas dynamics, taking into account the spectral transport of neutrinos in the framework of neutrino flux-limited diffusion. large-scale convection leads to an increase in the mean energy of the neutrinos from 10 to 15 mev, which is important for explaining supernovae, as well as for designing experiments on detecting high-energy neutrinos from supernovae. | large-scale instability during gravitational collapse and the escaping neutrino spectrum during a supernova explosion |
the present work constitutes a detailed study of neutral-current (nc) supernova-neutrino scattering off the stable even-even lead isotopes 204,206,208. this is a continuation of our previous work [almosly et al., phys. rev. c. 94, 044614 (2016), 10.1103/physrevc.94.044614] where we investigated charged-current processes on the same nuclei. as in the previous work, we have adopted the quasiparticle random-phase approximation (qrpa) as the theory framework and use three different skyrme interactions to build the involved nuclear wave functions. we test the skyrme forces by computing the location of the lowest-order isovector spin-multipole giant resonances and comparing with earlier calculations. we have computed the nc cross sections for (anti)neutrino energies up to 100 mev and estimated the nuclear responses to supernova (anti)neutrinos by folding the obtained cross sections by suitably parametrized fermi-dirac distributions of energies of the incoming (anti)neutrinos. we compare our results with results of earlier studies in the case of 208pb, which is the only lead isotope where earlier calculations are available. | neutral-current supernova-neutrino cross sections for 204,206,208pb calculated by skyrme quasiparticle random-phase approximation |
two accretion columns have been argued to form over the surface of a newborn millisecond magnetar for an extremely high accretion rate ≳1.8 ×10-2 m⊙ s-1 that may occur in the core collapse of a massive star. in this paper, we investigate the characteristics of these accretion columns and their gravitational wave (gw) radiation. for a typical millisecond magnetar (surface magnetic field strength b ∼1015 g and initial spin period p ∼1 ms ), we find (i) its accretion columns are cooled via neutrinos and can reach a height ∼1 km over the stellar surface; (ii) its column-induced characteristic gw strain is comparable to the sensitivities of the next-generation ground-based gw detectors within a horizon ∼1 mpc ; (iii) the magnetar can survive only a few tens of seconds; (iv) during the survival timescale, the height of the accretion columns increases rapidly to the peak and subsequently decreases slowly; (v) the column mass, characteristic gw strain, and maximum gw luminosity have simultaneous peaks in a similar rise-fall evolution. in addition, we find that the magnetar's spin evolution is dominated by the column accretion torque. a possible association with failed supernova is also discussed. | gravitational waves from newborn accreting millisecond magnetars |
we investigate a method to construct parametrized progenitor models for core-collapse supernova simulations. different from all modern core-collapse supernova studies, which rely on progenitor models from stellar evolution calculations, we follow the methodology of baron & cooperstein to construct initial models. choosing parametrized spatial distributions of entropy and electron fraction as a function of mass coordinate and solving the equation of hydrostatic equilibrium, we obtain the initial density structures of our progenitor models. first, we calculate structures with parameters fitting broadly the evolutionary model s11.2 of woosley et al. (2002). we then demonstrate the reliability of our method by performing general relativistic hydrodynamic simulations in spherical symmetry with the isotropic diffusion source approximation to solve the neutrino transport. our comprehensive parameter study shows that initial models with a small central entropy (≲0.4 kb nucleon-1) can explode even in spherically symmetric simulations. models with a large entropy (≳6 kb nucleon-1) in the si/o layer have a rather large explosion energy (∼4 × 1050 erg) at the end of the simulations, which is still rapidly increasing. | parametric initial conditions for core-collapse supernova simulations |
the detection of gravitational waves from core-collapse supernova (ccsn) explosions is a challenging task, yet to be achieved, in which it is key the connection between multiple messengers, including neutrinos and electromagnetic signals. in this work, we present a method for detecting these kind of signals based on machine learning techniques. we tested its robustness by injecting signals in the real noise data taken by the advanced ligo-virgo network during the second observation run, o2. we trained a newly developed mini-inception resnet neural network using time-frequency images corresponding to injections of simulated phenomenological signals, which mimic the waveforms obtained in 3d numerical simulations of ccsne. with this algorithm we were able to identify signals from both our phenomenological template bank and from actual numerical 3d simulations of ccsne. we computed the detection efficiency versus the source distance, obtaining that, for signal to noise ratio higher than 15, the detection efficiency is 70 % at a false alarm rate lower than 5%. we notice also that, in the case of o2 run, it would have been possible to detect signals emitted at 1 kpc of distance, whilst lowering down the efficiency to 60%, the event distance reaches values up to 14 kpc. | deep learning for multimessenger core-collapse supernova detection |
the deep underground neutrino experiment (dune), a 40-kton fiducial mass underground liquid argon time projection chamber experiment, will be sensitive to the electron-neutrino-flavor component of the burst of neutrinos expected from the next galactic core-collapse supernova. such an observation will bring unique insight into the astrophysics of core collapse as well as into the properties of neutrinos. the recent progress on detection and reconstruction of supernova burst neutrinos in dune, including the contribution of the light detection systems are presented. | core-collapse supernove burst neutrinos in dune |
there is an accepted approach to calculation of the neutrino flavor density-matrix in the halo of a supernova, in which neutrino amplitudes, not cross-sections, need to be followed carefully in the region above the region of frequent scatterings. the same reasoning and techniques, applied to the evolution of neutrino flavors and energy distributions in the early universe in the era of neutrino decoupling, leads to radical changes in the prediction of the effects of the neutrino-neutrino interaction. predictions for the production of sterile neutrinos, should they exist, will also be changed. | neutrino refractive effects during their decoupling era in the early universe |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.