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1
Hargrove, C. K., e D. J. Paterson. "Solar-neutrino neutral-current detection methods in the Sudbury neutrino observatory". Canadian Journal of Physics 69, n. 11 (1 novembre 1991): 1309–16. http://dx.doi.org/10.1139/p91-196.
Testo completoAbstract (sommario):
The Sudbury Neutrino Observatory will study the solar-neutrino problem through the detection of charged-current (CC), neutral-current (NC), and elastic-scattering (ES) interactions of solar neutrinos with heavy water. The measurement of the NC rate relative to the CC rate provides a nearly model-independent method of observing neutrino oscillations. The NC interaction breaks up the deuteron producing a neutron and a proton. The interaction rate in the original design is measured by observing Čerenkov light from showers produced by neutron-capture γ rays from the capture of the NC neutrons by a selected additive to the heavy water. These signals overlap the CC and ES signals, so that the measurement of the NC rate requires the subtraction of two signals obtained at different times. This paper describes our investigation of an alternate detection method in which the thermalized neutrons are captured by (n, α) or (n, p) reactions on light nuclei. The resulting charged-particle products are uniquely detected by scintillators or proportional counters, completely separating this NC signal from the CC and ES Čerenkov signals, thus simplifying its measurement, improving its significance, and allowing observation of otherwise unobservable short-term NC fluctuations. Although background rates for the new techniques have not yet been determined, the experimental advantages justify further development work.
2
Saez, M. M., O. Civitarese e M. E. Mosquera. "Neutrino mixing in nuclear rapid neutron-capture processes". International Journal of Modern Physics E 29, n. 04 (aprile 2020): 2050022. http://dx.doi.org/10.1142/s0218301320500226.
Testo completoAbstract (sommario):
A possible mechanism for the formation of heavy-mass elements in supernovae is the rapid neutron-capture-mechanism ([Formula: see text]-process). It depends upon the electron-fraction [Formula: see text], a quantity which is determined by beta-decay-rates. In this paper, we focus on the calculation of electroweak decay-rates in presence of massive neutrinos. The resulting expressions are then used to calculate nuclear reactions entering the rapid-neutron capture. We fix the astrophysical parameters to the case of a core-collapse supernova. The neutrino sector includes a mass scheme and mixing angles for active neutrinos, and also by including the mixing between active and sterile neutrinos. The results of the calculations show that the predicted abundances of heavy-mass nuclei are indeed affected by the neutrino mixing.
3
Chen, Bing-Guang, Tong Liu, Yan-Qing Qi, Bao-Quan Huang, Yun-Feng Wei, Tuan Yi, Wei-Min Gu e Li Xue. "Effects of Vertical Advection on Multimessenger Signatures of Black Hole Neutrino-dominated Accretion Flows in Compact Binary Coalescences". Astrophysical Journal 941, n. 2 (1 dicembre 2022): 156. http://dx.doi.org/10.3847/1538-4357/aca406.
Testo completoAbstract (sommario):
Abstract In the coalescence events of binary neutron star (NS) or a black hole (BH) and an NS, a BH hyperaccretion disk might be eventually formed. At very high mass accretion rates, MeV neutrinos will be emitted from this disk, which is called a neutrino-dominated accretion flow (NDAF). Neutrino annihilation in the space out of the disk is energetic enough to launch ultrarelativistic jets to power gamma-ray bursts. Moreover, vertical advection might exist in NDAFs, which can generate the magnetic buoyancy bubbles to release gamma-ray photons. In this paper, we visit the effects of the vertical advection in NDAFs on the disk structure and gamma-ray and neutrino luminosities for different accretion rates. Then we study the anisotropic emission of kilonovae and the following gravitational waves (GWs) driven by the gamma-ray photons and neutrinos from NDAFs. Comparing NDAFs without vertical advection, the neutrino luminosity and GW strains slightly decrease for the case with vertical advection, and the kilonovae will be brightened by the injected gamma-ray photons. The future joint multimessenger observations might distinguish whether the vertical advection exists in NDAFs or not after compact binary coalescences.
4
Papoulias, D. K., e T. S. Kosmas. "Nuclear study of the exotic neutrino interactions". HNPS Proceedings 22 (8 marzo 2019): 79. http://dx.doi.org/10.12681/hnps.1934.
Testo completoAbstract (sommario):
Open neutrino physics issues require precision studies, both theoretical and experimental ones, and towards this aim coherent neutral current neutrino-nucleus scattering events are expected to be observed soon. In this work, we explore ν -nucleus processes from a nuclear theory point of view and obtain results with high confidence level based on accurate nuclear structure cross sections calculations. The present study explores the differential event rates as well as the total number of events expected to be measured by nuclear detectors, indicating measurable rates. We concentrate on the possibility of detecting supernova neutrinos by using massive detectors like those of the GERDA and SuperCDMS dark matter experiments and at spallation neutron source facilities (at Oak Ridge National Lab) by the COHERENT experiment.
5
Aiello, S., A. Albert, S. Alves Garre, Z. Aly, A. Ambrosone, F. Ameli, M. Andre et al. "Searches for neutrino counterparts of gravitational waves from the LIGO/Virgo third observing run with KM3NeT". Journal of Cosmology and Astroparticle Physics 2024, n. 04 (1 aprile 2024): 026. http://dx.doi.org/10.1088/1475-7516/2024/04/026.
Testo completoAbstract (sommario):
Abstract The KM3NeT neutrino telescope is currently being deployed at two different sites in the Mediterranean Sea. First searches for astrophysical neutrinos have been performed using data taken with the partial detector configuration already in operation. The paper presents the results of two independent searches for neutrinos from compact binary mergers detected during the third observing run of the LIGO and Virgo gravitational wave interferometers. The first search looks for a global increase in the detector counting rates that could be associated with inverse beta decay events generated by MeV-scale electron anti-neutrinos. The second one focuses on upgoing track-like events mainly induced by muon (anti-)neutrinos in the GeV–TeV energy range. Both searches yield no significant excess for the sources in the gravitational wave catalogs. For each source, upper limits on the neutrino flux and on the total energy emitted in neutrinos in the respective energy ranges have been set. Stacking analyses of binary black hole mergers and neutron star-black hole mergers have also been performed to constrain the characteristic neutrino emission from these categories.
6
Walg, Jonathan, Jon Feldman e Itzhak Orion. "Decay rate changes in radioactive gamma emission as affected by 18 MeV proton cyclotron". Nuclear Technology and Radiation Protection 39, n. 1 (2024): 1–11. http://dx.doi.org/10.2298/ntrp2401001w.
Testo completoAbstract (sommario):
Previous efforts to investigate changes in the decay constants of radioactive nuclides discovered that solar flares can temporarily alter radioactive decay rates. Thus, discerning whether external factors affect radioactive decay rates is vital for understanding nuclear processes. This study sought to explore the effect of neutrinos on radioactive nuclei by constructing a gamma radiation detection system that employs a radioactive source in front of a neutrino emission system. Responding to cyclotron operations, each of the four detection systems registered gamma count rate decreases. The results of this study confirm that rises in neutrino flux affected the decay rates of the examined radioactive nuclides. Here we provide significant evidence that neutrinos affect the radioactive decay process. Neutrino detection is challenging due to the minuscule absorption in a stable nucleus. However, the study found a greater probability of radionuclides interaction with the neutrino.
7
DUTTA, SHARADA IYER, MARY HALL RENO e INA SARCEVIC. "ULTRAHIGH ENERGY NEUTRINOS". International Journal of Modern Physics A 18, n. 22 (10 settembre 2003): 4085–96. http://dx.doi.org/10.1142/s0217751x03017385.
Testo completoAbstract (sommario):
The ultrahigh energy neutrino cross section is well understood in the standard model for neutrino energies up to 1012 GeV, Tests of neutrino oscillations (νμ ↔ ντ) from extragalactic sources of neutrinos are possible with large underground detectors. Measurements of horizontal air shower event rates at neutrino energies above 1010 GeV will be able to constrain nonstandard model contributions to the neutrino-nucleon cross section, e.g., from mini-black hole production.
8
Biondini, S., D. Bödeker, N. Brambilla, M. Garny, J. Ghiglieri, A. Hohenegger, M. Laine et al. "Status of rates and rate equations for thermal leptogenesis". International Journal of Modern Physics A 33, n. 05n06 (28 febbraio 2018): 1842004. http://dx.doi.org/10.1142/s0217751x18420046.
Testo completoAbstract (sommario):
In many realizations of leptogenesis, heavy right-handed neutrinos play the main role in the generation of an imbalance between matter and antimatter in the early Universe. Hence, it is relevant to address quantitatively their dynamics in a hot and dense environment by taking into account the various thermal aspects of the problem at hand. The strong washout regime offers an interesting framework to carry out calculations systematically and reduce theoretical uncertainties. Indeed, any matter–antimatter asymmetry generated when the temperature of the hot plasma [Formula: see text] exceeds the right-handed neutrino mass scale [Formula: see text] is efficiently erased, and one can focus on the temperature window [Formula: see text]. We review recent progress in the thermal field theoretic derivation of the key ingredients for the leptogenesis mechanism: the right-handed neutrino production rate, the CP asymmetry in the heavy-neutrino decays and the washout rates. The derivation of evolution equations for the heavy-neutrino and lepton-asymmetry number densities, their rigorous formulation and applicability are also discussed.
9
LIU, JING-JING, ZHI-QUAN LUO, HONG-LIN LIU e XIANG-JUN LAI. "NEUTRINO ENERGY LOSS ON IRON GROUP NUCLEI BY ELECTRON CAPTURE IN STRONG MAGNETIC FIELD AT THE CRUSTS OF NEUTRON STARS". International Journal of Modern Physics A 22, n. 19 (30 luglio 2007): 3305–15. http://dx.doi.org/10.1142/s0217751x07037287.
Testo completoAbstract (sommario):
The neutrino energy loss rates on iron group nuclei by electron capture are calculated in a strong magnetic field at the crusts of Neutron stars. The results show that the magnetic field has only a slight effect on the neutrino energy loss rates in a range of 108–1013 G on surfaces of the most neutron stars. Whereas for some magnetars which range of the magnetic field is 1013–1018 G, the neutrino energy loss rates of the most iron group nuclei would be debased greatly and may be even decreased for 4 orders of magnitude by the strong magnetic field.
10
Papoulias, D. K., e T. S. Kosmas. "Standard and Nonstandard Neutrino-Nucleus Reactions Cross Sections and Event Rates to Neutrino Detection Experiments". Advances in High Energy Physics 2015 (2015): 1–17. http://dx.doi.org/10.1155/2015/763648.
Testo completoAbstract (sommario):
In this work, we exploreν-nucleus processes from a nuclear theory point of view and obtain results with high confidence level based on accurate nuclear structure cross sections calculations. Besides cross sections, the present study includes simulated signals expected to be recorded by nuclear detectors and differential event rates as well as total number of events predicted to be measured. Our original cross sections calculations are focused on measurable rates for the standard model process, but we also perform calculations for various channels of the nonstandard neutrino-nucleus reactions and come out with promising results within the current upper limits of the corresponding exotic parameters. We concentrate on the possibility of detecting (i) supernova neutrinos by using massive detectors like those of the GERDA and SuperCDMS dark matter experiments and (ii) laboratory neutrinos produced near the spallation neutron source facilities (at Oak Ridge National Lab) by the COHERENT experiment. Our nuclear calculations take advantage of the relevant experimental sensitivity and employ the severe bounds extracted for the exotic parameters entering the Lagrangians of various particle physics models and specifically those resulting from the charged lepton flavour violatingμ-→e-experiments (Mu2e and COMET experiments).
11
Bergström, Lars, Joakim Edsjö e Paolo Gondolo. "Indirect neutralino detection rates in neutrino telescopes". Physical Review D 55, n. 4 (15 febbraio 1997): 1765–70. http://dx.doi.org/10.1103/physrevd.55.1765.
Testo completo
12
Sridhar, Navin, Brian D. Metzger e Ke Fang. "High-energy Neutrinos from Gamma-Ray-faint Accretion-powered Hypernebulae". Astrophysical Journal 960, n. 1 (27 dicembre 2023): 74. http://dx.doi.org/10.3847/1538-4357/ad03e8.
Testo completoAbstract (sommario):
Abstract Hypernebulae are inflated by accretion-powered winds accompanying hyper-Eddington mass transfer from an evolved post-main-sequence star onto a black hole or neutron star companion. The ions accelerated at the termination shock—where the collimated fast disk winds and/or jet collide with the slower, wide-angled wind-fed shell—can generate high-energy neutrinos via hadronic proton–proton reactions, and photohadronic (p γ) interactions with the disk thermal and Comptonized nonthermal background photons. It has been suggested that some fast radio bursts (FRBs) may be powered by such short-lived jetted hyper-accreting engines. Although neutrino emission associated with the millisecond duration bursts themselves is challenging to detect, the persistent radio counterparts of some FRB sources—if associated with hypernebulae—could contribute to the high-energy neutrino diffuse background flux. If the hypernebula birth rate follows that of stellar-merger transients and common envelope events, we find that their volume-integrated neutrino emission—depending on the population-averaged mass-transfer rates—could explain up to ∼25% of the high-energy diffuse neutrino flux observed by the IceCube Observatory and the Baikal Gigaton Volume Detector Telescope. The time-averaged neutrino spectrum from hypernebula—depending on the population parameters—can also reproduce the observed diffuse neutrino spectrum. The neutrino emission could in some cases furthermore extend to >100 PeV, detectable by future ultra-high-energy neutrino observatories. The large optical depth through the nebula to Breit–Wheeler (γ γ) interaction attenuates the escape of GeV–PeV gamma rays coproduced with the neutrinos, rendering these gamma-ray-faint neutrino sources, consistent with the Fermi observations of the isotropic gamma-ray background.
13
Akita, Kensuke, e Masahide Yamaguchi. "A Review of Neutrino Decoupling from the Early Universe to the Current Universe". Universe 8, n. 11 (25 ottobre 2022): 552. http://dx.doi.org/10.3390/universe8110552.
Testo completoAbstract (sommario):
We review the distortions of spectra of relic neutrinos due to the interactions with electrons, positrons, and neutrinos in the early universe. We solve integro-differential kinetic equations for the neutrino density matrix, including vacuum three-flavor neutrino oscillations, oscillations in electron and positron background, a collision term and finite temperature corrections to electron mass and electromagnetic plasma up to the next-to-leading order O(e3). After that, we estimate the effects of the spectral distortions in neutrino decoupling on the number density and energy density of the Cosmic Neutrino Background (CνB) in the current universe, and discuss the implications of these effects on the capture rates in direct detection of the CνB on tritium, with emphasis on the PTOLEMY-type experiment. In addition, we find a precise value of the effective number of neutrinos, Neff=3.044. However, QED corrections to weak interaction rates at order O(e2GF2) and forward scattering of neutrinos via their self-interactions have not been precisely taken into account in the whole literature so far. Recent studies suggest that these neglections might induce uncertainties of ±(10−3−10−4) in Neff.
14
BECKER, J. K., e W. RHODE. "INVESTIGATION OF EVENT RATES FOR DIFFERENT DETECTOR ARRAYS AND VARIOUS EXTREMELY HIGH ENERGY MODELS". International Journal of Modern Physics A 21, supp01 (luglio 2006): 20–24. http://dx.doi.org/10.1142/s0217751x06033295.
Testo completoAbstract (sommario):
New detection methods for extremely high energy (EHE) neutrinos are being discussed. In this paper, the comparison of different detection methods at energies E > 107.5 GeV are examined, using various neutrino flux predictions. Arrays for acoustic and radio signals from neutrino induced electromagnetic cascades as well as the IceCube array with additional strings ("IceCube Plus") are investigated with effective volumes as given in 5,6. The depth of the detector below the Earth's surface are examined with respect to the absorption of a potential neutrino signal by the Earth. It can be shown that absorption plays an important role and that an array of acoustic and radio antennas should preferably be put at shallow depths of ~ 500 m depth. The detection potential at this depth ranges from several up to tens of events at EHEs depending on the source of the neutrino flux.
15
Misch, G. Wendell, Yang Sun e George Fuller. "Nuclear Neutrino Spectra in Late Stellar Evolution". EPJ Web of Conferences 178 (2018): 04005. http://dx.doi.org/10.1051/epjconf/201817804005.
Testo completoAbstract (sommario):
Neutrinos are the principle carriers of energy in massive stars, beginning from core carbon burning and continuing through core collapse and after the core bounce. In fact, it may be possible to detect neutrinos from nearby pre-supernova stars. Therefore, it is of great interest to understand the neutrino energy spectra from these stars. Leading up to core collapse, beginning around core silicon burning, nuclei become dominant producers of neutrinos, particularly at high neutrino energy, so a systematic study of nuclear neutrino spectra is desirable. We have done such a study, and we present our sd-shell model calculations of nuclear neutrino energy spectra for nuclei in the mass number range A = 21 – 35. Our study includes neutrinos produced by charged lepton capture, charged lepton emission, and neutral current nuclear deexcitation. Previous authors have tabulated the rates of charged current nuclear weak interactions in astrophysical conditions, but the present work expands on this not only by providing neutrino energy spectra, but also by including the heretofore untabulated neutral current de-excitation neutrino pairs.
16
Saez, M. M., K. J. Fushimi, M. E. Mosquera e O. Civitarese. "Limits on active-sterile neutrino mixing parameters using heavy nuclei abundances". International Journal of Modern Physics E 30, n. 04 (aprile 2021): 2150028. http://dx.doi.org/10.1142/s0218301321500282.
Testo completoAbstract (sommario):
The production of heavy-mass elements due to the rapid neutron-capture mechanism ([Formula: see text]-process) is associated with astrophysical scenarios, such as supernovae and neutron-star mergers. In the [Formula: see text]-process the capture of neutrons is followed by [Formula: see text]-decays until nuclear stability is reached. A key element in the chain of nuclear weak-decays leading to the production of isotopes may be the change of the parameters controlling the neutrino sector, due to the mixing of active and sterile species. In this work, we have addressed this question and calculated [Formula: see text]-decay rates for the nuclei involved in the [Formula: see text]-process chains as a function of the neutrino mixing parameters. These rates are then used in the calculation of the abundance of the heavy elements produced in core-collapse supernova and in neutron-star mergers, starting from different initial mass-fraction distributions. The analysis shows that the core-collapse supernova environment contributes with approximately [Formula: see text] of the total heavy nuclei abundance while the neutron-star merger contributes with about [Formula: see text] of it. Using available experimental data we have performed a statistical analysis to set limits on the active-sterile neutrino mixing angle and found a best-fit value [Formula: see text], a value comparable with those found in other studies reported in the literature.
17
Akaho, Ryuichiro, Hiroki Nagakura e Thierry Foglizzo. "Detectability of Late-time Supernova Neutrinos with Fallback Accretion onto Protoneutron Star". Astrophysical Journal 960, n. 2 (1 gennaio 2024): 116. http://dx.doi.org/10.3847/1538-4357/ad118c.
Testo completoAbstract (sommario):
Abstract We investigate the late-time neutrino emission powered by fallback mass accretion onto a protoneutron star (PNS), using neutrino radiation-hydrodynamic simulations with full Boltzmann neutrino transport. We follow the time evolution of the accretion flow onto the PNS until the system reaches a quasi-steady state. A standing shock wave is commonly formed in the accretion flow, whereas the shock radius varies depending on the mass accretion rate and the PNS mass. A sharp increase in temperature emerges in the vicinity of the PNS (∼10 km), which characterizes neutrino emission. Both the neutrino luminosity and the average energy become higher with increasing mass accretion rate and PNS mass. The mean energy of the emitted neutrinos is in the range of 10 ≲ ϵ ≲ 20 MeV, which is higher than that estimated from PNS cooling models (≲10 MeV). Assuming a distance to core-collapse supernova of 10 kpc, we quantify neutrino event rates for Super-Kamiokande (Super-K) and Deep Underground Neutrino Experiment (DUNE). The estimated detection rates are well above the background, and their energy-dependent features are qualitatively different from those expected from PNS cooling models. Another notable feature is that the neutrino emission is strongly flavor dependent, exhibiting that the neutrino event rate hinges on the neutrino oscillation model. We estimate them in the case with the adiabatic Mikheev–Smirnov–Wolfenstein model, and show that the normal and inverted mass hierarchy offer a large number of neutrino detections in Super-K and DUNE, respectively. Hence the simultaneous observation with Super-K and DUNE of fallback neutrinos will provide a strong constraint on the neutrino mass hierarchy.
18
NABI, JAMEEL-UN. "NEUTRINO AND ANTINEUTRINO ENERGY LOSS RATES IN MASSIVE STARS DUE TO ISOTOPES OF TITANIUM". International Journal of Modern Physics E 19, n. 01 (gennaio 2010): 63–77. http://dx.doi.org/10.1142/s0218301310014716.
Testo completoAbstract (sommario):
Weak interaction rates on titanium isotopes are important during the late phases of evolution of massive stars. A search was made for key titanium isotopes from available literature and a microscopic calculation of weak rates of these nuclei were performed using the proton-neutron quasiparticle random phase approximation (pn-QRPA) theory. Earlier the author presented the stellar electron capture rates on titanium isotopes. In this paper I present the neutrino and antineutrino energy loss rates due to capture and decay rates on isotopes of titanium in stellar environment. Accurate estimate of neutrino energy loss rates are needed for the study of the late stages of the stellar evolution, in particular for cooling of neutron stars and white dwarfs. The results are also compared against previous calculations. At high stellar temperatures the calculated neutrino and antineutrino energy loss rates are bigger by more than two orders of magnitude as compared to the large scale shell model results and favor stellar cores with lower entropies. This study can prove useful for core-collapse simulators.
19
STAŚTO, ANNA M. "ULTRAHIGH ENERGY NEUTRINO PHYSICS". International Journal of Modern Physics A 19, n. 03 (30 gennaio 2004): 317–40. http://dx.doi.org/10.1142/s0217751x04017082.
Testo completoAbstract (sommario):
Ultrahigh energy neutrinos can provide important information about the distant astronomical objects and the origin of the Universe. Precise knowledge about neutrino interactions and production rates is essential for estimating background, expected fluxes and detection probabilities. In this paper we review the applications of the high energy QCD to the calculations of the interaction cross-sections of the neutrinos. We also study the production of the ultrahigh energy neutrinos in the atmosphere due to the charm and beauty decays.
20
Wang, Edward. "Resonant spin-flavor precession of sterile neutrinos". Journal of Cosmology and Astroparticle Physics 2024, n. 05 (1 maggio 2024): 056. http://dx.doi.org/10.1088/1475-7516/2024/05/056.
Testo completoAbstract (sommario):
Abstract We analyze the impact of resonant conversions mediated by non-vanishing magnetic moments between active neutrinos and a heavy sterile neutrino on the supernova neutrino flux. We present the level-crossing scheme for such a scenario and derive the neutrino fluxes after conversion, paying particular attention to the order in which the resonances occur. We then compute the expected event rates from the neutronization burst of a future supernova at DUNE and Hyper-Kamiokande to derive new constraints on the neutrino magnetic moment. With this, we find a sensitivity down to a few 10-15 μB for a sterile neutrino in the O(eV) mass range.
21
Kullmann, I., S. Goriely, O. Just, R. Ardevol-Pulpillo, A. Bauswein e H.-T. Janka. "Dynamical ejecta of neutron star mergers with nucleonic weak processes I: nucleosynthesis". Monthly Notices of the Royal Astronomical Society 510, n. 2 (24 novembre 2021): 2804–19. http://dx.doi.org/10.1093/mnras/stab3393.
Testo completoAbstract (sommario):
ABSTRACT We present a coherent study of the impact of neutrino interactions on the r-process element nucleosynthesis and the heating rate produced by the radioactive elements synthesized in the dynamical ejecta of neutron star–neutron star (NS–NS) mergers. We have studied the material ejected from four NS–NS merger systems based on hydrodynamical simulations which handle neutrino effects in an elaborate way by including neutrino equilibration with matter in optically thick regions and re-absorption in optically thin regions. We find that the neutron richness of the dynamical ejecta is significantly affected by the neutrinos emitted by the post-merger remnant, in particular when compared to a case neglecting all neutrino interactions. Our nucleosynthesis results show that a solar-like distribution of r-process elements with mass numbers $A \gtrsim 90$ is produced, including a significant enrichment in Sr and a reduced production of actinides compared to simulations without inclusion of the nucleonic weak processes. The composition of the dynamically ejected matter as well as the corresponding rate of radioactive decay heating are found to be rather independent of the system mass asymmetry and the adopted equation of state. This approximate degeneracy in abundance pattern and heating rates can be favourable for extracting the ejecta properties from kilonova observations, at least if the dynamical component dominates the overall ejecta. Part II of this work will study the light curve produced by the dynamical ejecta of our four NS merger models.
22
Gizzi, D., C. Lundman, E. O’Connor, S. Rosswog e A. Perego. "Calibration of the Advanced Spectral Leakage scheme for neutron star merger simulations, and extension to smoothed-particle hydrodynamics". Monthly Notices of the Royal Astronomical Society 505, n. 2 (21 maggio 2021): 2575–93. http://dx.doi.org/10.1093/mnras/stab1432.
Testo completoAbstract (sommario):
ABSTRACT We calibrate a neutrino transport approximation, called Advanced Spectral Leakage (ASL), with the purpose of modelling neutrino-driven winds in neutron star mergers. Based on a number of snapshots, we gauge the ASL parameters by comparing against both the two-moment (M1) scheme implemented in the flash code and the Monte Carlo neutrino code sedonu. The ASL scheme contains three parameters, the least robust of which results to be a blocking parameter for electron neutrinos and antineutrinos. The parameter steering the angular distribution of neutrino heating is recalibrated compared to the earlier work. We also present a new, fast and mesh-free algorithm for calculating spectral optical depths, which, when using smoothed-particle hydrodynamics (SPH), makes the neutrino transport completely particle-based. We estimate a speed-up of a factor of ≳100 in the optical depth calculation when comparing to a grid-based approach. In the suggested calibration we recover luminosities and mean energies within $25{{\ \rm per\ cent}}$. A comparison of the rates of change of internal energy and electron fraction in the neutrino-driven wind suggests comparable accuracies of ASL and M1, but a higher computational efficiency of the ASL scheme. We estimate that the ratio between the CPU hours spent on the ASL neutrino scheme and those spent on the hydrodynamics is ≲0.8 per time-step when considering the SPH code magma2 as source code for the Lagrangian hydrodynamics, to be compared with a factor of 10 from the M1 in flash.
23
Zegarelli, Angela, Michela Fasano, Silvia Celli, Dafne Guetta, Antonio Capone e Irene Di Palma. "Neutrino predictions from choked Gamma-Ray Bursts and comparison with the observed cosmic diffuse neutrino flux". EPJ Web of Conferences 280 (2023): 09005. http://dx.doi.org/10.1051/epjconf/202328009005.
Testo completoAbstract (sommario):
The strong constraints from the Fermi-LAT data on the isotropic gamma-ray background suggest that the neutrinos observed by IceCube might possibly come from sources that are hidden to gamma-ray observations. A possibility emerged in recent years is that neutrinos may come from jets of collapsing massive stars which fail to break out of the stellar envelope, and for this reason they are known as choked jets, or choked Gamma-Ray Bursts (GRBs). We here show our predictions of neutrino flux and spectrum expected from these sources, focusing on Type II SNe, through detailed calculations of pγ interactions and accounting for all the neutrino production channels and scattering angles. We provide predictions of expected event rates for ANTARES, IceCube, and the next generation neutrino telescope KM3NeT.We also compute the contribution of the choked GRB population to the diffuse astrophysical neutrino flux, thus providing constraints on the local rate of this source population as to reproduce the observed neutrino flux.
24
Hernández-Molinero, Beatriz, Carmelita Carbone, Raul Jimenez e Carlos Peña Garay. "Cosmic background neutrinos deflected by gravity: DEMNUni simulation analysis". Journal of Cosmology and Astroparticle Physics 2024, n. 01 (1 gennaio 2024): 006. http://dx.doi.org/10.1088/1475-7516/2024/01/006.
Testo completoAbstract (sommario):
Abstract The local supercluster acts as a gravity deflection source for cosmic background neutrinos. This deflection by gravity changes the neutrino helicity and therefore has important consequences for ground based tritium capture experiments aimed at determining if the neutrino is Dirac or Majorana. Here we explore the deflection effect of the local supercluster using two simulations from the DEMNUni suite characterised by very different mass resolutions, as they are both filled with 20483 dark matter particles (and an equal number of massive neutrino particles) but have comoving volumes of (2 h -1Gpc)3 and (500 h -1Mpc)3, respectively. We reaffirm our previous results and show that the lightest neutrinos are ultra-relativistic enough to suffer little deflection by gravity and at the same time not relativistic enough to achieve the same capture rate for Dirac and Majorana cases. This means that the capture rate in Ptolemy-like experiments will be sensitive to the neutrino nature and that gravity deflection enlarges the difference between Majorana and Dirac rates. Moreover, using the relation between mass and momentum of the neutrinos frozen Fermi-Dirac distribution, but taking into consideration gravity corrections, we are able to calculate the deflection angle for different neutrino masses from the same set of neutrinos obtained from the simulation. Doing so, we provide a formula to compute the deflection angle for any neutrino mass, such that when cosmology detects an absolute neutrino mass, precise predictions can be made for tritium ground-based detectors on Earth aimed to determine neutrinos nature.
25
Huang, Jihong, e Shun Zhou. "Helicity-changing decays of cosmological relic neutrinos". Journal of Cosmology and Astroparticle Physics 2024, n. 09 (1 settembre 2024): 067. http://dx.doi.org/10.1088/1475-7516/2024/09/067.
Testo completoAbstract (sommario):
Abstract In this paper, we examine the possibility that massive neutrinos are unstable due to their invisible decays ν i → ν j + ϕ, where ν i and ν j (for i, j = 1, 2, 3) are any two of neutrino mass eigenstates with masses m i > m i and ϕ is a massless Nambu-Goldstone boson, and explore the implications for the detection of cosmological relic neutrinos in the present Universe. First, we carry out a complete calculation of neutrino decay rates in the general case where the individual helicities of parent and daughter neutrinos are specified. Then, the invisible decays of cosmological relic neutrinos are studied and their impact on the capture rates on the beta-decaying nuclei (e.g., ν e + 3H → 3He + e -) is analyzed. The invisible decays of massive neutrinos could substantially change the capture rates in the PTOLEMY-like experiments when compared to the case of stable neutrinos. In particular, we find that the helicity-changing decays of Dirac neutrinos play an important role whereas those of Majorana neutrinos have no practical effects. However, if a substantial fraction of heavier neutrinos decay into the lightest one, the detection of relic neutrinos will require a much higher energy resolution and thus be even more challenging.
26
Li, Gexing, e Zhihong Li. "A Promising Approach for Determining Neutrino Mass Hierarchy by Using Supernova Neutrino Detections". Astrophysical Journal 976, n. 2 (25 novembre 2024): 206. http://dx.doi.org/10.3847/1538-4357/ad8cd9.
Testo completoAbstract (sommario):
Abstract The determination of neutrino mass hierarchy is crucial for particle physics, astrophysics, and cosmology. In this work, we propose an easy-to-use method to determine the neutrino hierarchy based on core-collapse supernova (CCSN) neutrino detections. By analyzing the expected event rates of the neutrino burst at a terrestrial water Cherenkov detector, we found that the event rates predicted by the normal and inverted hierarchy models have marked differences in the neutrino energy range 10 ∼ 20 MeV and the postbounce time <0.5 s. Within this specific energy and time range, the analytical relationship between the cumulative event number and proto–neutron star (PNS) baryon mass is extracted. Based on the normal and inverted hierarchy models, two different PNS masses can be inferred from this relationship by using the time profile of neutrino events. Then, the neutrino hierarchy can be determined by comparing the PNS mass inferred from the neutrino detections and the electromagnetic or gravitational-wave channels. Furthermore, the nonadiabatic part of the Mikheyev–Smirnov–Wolfenstein flavor conversions may also be quantified with this method, which would be very helpful for the studies of the explosion mechanism and nucleosynthesis of CCSNe.
27
Bottaro, Salvatore, Andrea Caputo e Damiano F. G. Fiorillo. "Neutrino emission in cold neutron stars: Bremsstrahlung and modified urca rates reexamined". Journal of Cosmology and Astroparticle Physics 2024, n. 11 (1 novembre 2024): 015. http://dx.doi.org/10.1088/1475-7516/2024/11/015.
Testo completoAbstract (sommario):
Abstract Neutrino emission in cold neutron stars is dominated by the modified urca (murca) process and nucleon-nucleon bremsstrahlung. The standard emission rates were provided by Friman and Maxwell in 1979, effectively based on a chiral Lagrangian framework with pion and rho meson exchange, supplemented by Landau parameters to describe short-range interactions. We reevaluate these rates within the same framework, correcting several errors and removing unnecessary simplifications, notably the triangular approximation — where the Fermi momenta of protons and leptons negligible compared to that of neutrons — in MURCA, and quantify their importance. The impact of rho meson exchange, previously argued to cancel with interference effects, is actually quite relevant. Altogether, the cooling rates are reduced by as much as a factor 2. We provide comprehensive analytical formulas encompassing all contributions, designed for straightforward numerical implementation. Our results are particularly relevant for studies of physics beyond the standard model, where the emission of new particles — such as axions — is typically computed within the same framework we adopt here.
28
Dzhioev, A. A., A. V. Yudin, N. V. Dunina-Barkovskaya e A. I. Vdovin. "Neutrino Spectrum and Energy Loss Rates Due to Weak Processes on Hot 56Fe in Pre-Supernova Environment". Particles 6, n. 3 (28 giugno 2023): 682–92. http://dx.doi.org/10.3390/particles6030041.
Testo completoAbstract (sommario):
Applying TQRPA calculations of Gamow–Teller strength functions in hot nuclei, we compute the (anti)neutrino spectra and energy loss rates arising from weak processes on hot 56Fe under pre-supernova conditions. We use a realistic pre-supernova model calculated by the stellar evolution code MESA. Taking into account both charged and neutral current processes, we demonstrate that weak reactions with hot nuclei can produce high-energy (anti)neutrinos. We also show that, for hot nuclei, the energy loss via (anti)neutrino emission is significantly larger than that for nuclei in their ground state. It is found that the neutral current de-excitation via the νν¯-pair emission is presumably a dominant source of antineutrinos. In accordance with other studies, we confirm that the so-called single-state approximation for neutrino spectra might fail under certain pre-supernova conditions.
29
Gaba, R., S. Jaydip, V. Bhatnagar e S. Jyotsna. "Prediction of supernova neutrino signals by detectors and its future challenges". Journal of Instrumentation 18, n. 07 (1 luglio 2023): C07003. http://dx.doi.org/10.1088/1748-0221/18/07/c07003.
Testo completoAbstract (sommario):
Abstract Supernova neutrinos produced during a core collapse of a massive star, carries 99% of the energy produced during the violent phenomenon. These neutrinos are weakly interacting massive particles and can provide useful information for both particle physics (neutrino oscillations parameters) and astrophysics (explosion mechanism). This information can be used to explore physics beyond the standard model. Neutrinos escape from the supernova core hours before the light, so a neutrino signal providing information about supernova direction can enable early observation. The current generation of detectors, like, Super-Kamiokande (Super-K), Large Volume Detector (LVD), Borexino, Kamioka Liquid Scintillator Antineutrino Detector (KamLAND), and IceCube, as well as HALO, Daya Bay(reactor neutrino experiment) and NuMI Off-Axis νe Appearance experiment (NOvA), have the ability to detect only a few orders of magnitude of events and the next generation experiment like, Hyper-Kamiokande (Hyper-K), Deep Underground Neutrino Experiment (DUNE), and Jiangmen Underground Neutrino Observatory (JUNO) will have yet another order of magnitude in reach, as well as richer flavor sensitivity. This work will present a Monte Carlo based study using the SNOwGLoBES [1] package, which is used to estimate the event rate using folded fluxes, cross-sections, and detector smearing to determine mean expected neutrino interaction signals in multiple current and future detectors. A study is carried out for the calculation of core-collapse neutrino event rates in realistic detectors for different flux models, effects of different parameters on flux and its variation with time.
30
Albuquerque, Ivone F. M., Jodi Lamoureux e George F. Smoot. "Astrophysical Neutrino Event Rates and Sensitivity for Neutrino Telescopes". Astrophysical Journal Supplement Series 141, n. 1 (luglio 2002): 195–209. http://dx.doi.org/10.1086/340281.
Testo completo
31
Wu, Quan-feng, e Xun-Jie Xu. "Shedding light on neutrino self-interactions with solar antineutrino searches". Journal of Cosmology and Astroparticle Physics 2024, n. 02 (1 febbraio 2024): 037. http://dx.doi.org/10.1088/1475-7516/2024/02/037.
Testo completoAbstract (sommario):
Abstract Solar antineutrinos are absent in the standard solar model prediction. Consequently, solar antineutrino searches emerge as a powerful tool to probe new physics capable of converting neutrinos into antineutrinos. In this study, we highlight that neutrino self-interactions, recently gaining considerable attention due to their cosmological and astrophysical implications, can lead to significant solar antineutrino production. We systematically explore various types of four-fermion effective operators and light scalar mediators for neutrino self-interactions. By estimating the energy spectra and event rates of solar antineutrinos at prospective neutrino detectors such as JUNO, Hyper-Kamiokande, and THEIA, we reveal that solar antineutrino searches can impose stringent constraints on neutrino self-interactions and probe the parameter space favored by the Hubble tension.
32
DEV, S., e JYOTI DHAR SHARMA. "THE STATUS OF THE SOLAR NEUTRINO PROBLEM IN THE RESONANT SPIN-FLAVOR PRECESSION SCENARIO WITH TWISTING SOLAR MAGNETIC FIELDS". Modern Physics Letters A 15, n. 22n23 (30 luglio 2000): 1445–60. http://dx.doi.org/10.1142/s0217732300001870.
Testo completoAbstract (sommario):
Resonant spin-flavor precession scenario with twisting solar magnetic fields has been confronted with the solar neutrino data from various ongoing experiments. In particular, the anticorrelation apparent in the Homestake solar neutrino data has been taken seriously to constrain the twisting profiles of the magnetic field in the convective zone of the Sun. The twisting profiles, thus derived, have been used to calculate the neutrino detection rates for the Homestake, Kamiokande (super-Kamiokande) and the gallium experiments. It is found that the presence of twisting reduces the degree of anticorrelation in all the solar neutrino experiments. However, the anticorrelation in the Homestake experiment is expected to be more pronounced. Moreover, the anticorrelation of solar neutrino flux emerging from the southern solar hemisphere is expected to be stronger than that for the neutrinos emerging from the northern solar hemisphere.
33
Riquelme, M., A. Reisenegger, O. Espinosa e C. O. Dib. "Neutrino emission rates in highly magnetized neutron stars revisited". Astronomy & Astrophysics 439, n. 2 (29 luglio 2005): 427–32. http://dx.doi.org/10.1051/0004-6361:20042263.
Testo completo
34
Bahcall, J. N., e M. Cribier. "The Standard Solar Model". International Astronomical Union Colloquium 121 (1990): 21–41. http://dx.doi.org/10.1017/s0252921100067798.
Testo completoAbstract (sommario):
AbstractThe main features of standard solar models, the logic of the calculations, and some of the important results concerning solar neutrinos experiments are given. The input parameters that cause the greatest uncertainties in the calculated neutrino fluxes are the nuclear rection rates, the chemical abundances, the radiative opacity, and the equation of state. This article is based, with permission of the publisher, on Chapters 1 and 4 of Neutrino Astrophysics by J. N. Bahcall, Cambridge University Press (1989).
35
Pascal, A., J. Novak e M. Oertel. "Proto-neutron star evolution with improved charged-current neutrino–nucleon interactions". Monthly Notices of the Royal Astronomical Society 511, n. 1 (8 gennaio 2022): 356–70. http://dx.doi.org/10.1093/mnras/stac016.
Testo completoAbstract (sommario):
ABSTRACT We perform simulations of the Kelvin–Helmholtz cooling phase of proto-neutron stars with a new numerical code in spherical symmetry and using the quasi-static approximation. We use for the first time the full set of charged-current neutrino–nucleon reactions, including neutron decay and modified Urca processes, together with the energy-dependent numerical representation for the inclusion of nuclear correlations with random phase approximation. Moreover, convective motions are taken into account within the mixing length theory. As we vary the assumptions for computing neutrino–nucleon reaction rates, we show that the dominant effect on the cooling time-scale, neutrino signal, and composition of the neutrino-driven wind comes from the inclusion of convective motion. Computation of nuclear correlations within the random phase approximation, as compared to mean field approach, has a relatively small impact.
36
Jentschura, Ulrich D., e Robert Ehrlich. "Lepton Pair Čerenkov Radiation Emitted by Tachyonic Neutrinos: Lorentz-Covariant Approach and IceCube Data". Advances in High Energy Physics 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/4764981.
Testo completoAbstract (sommario):
Current experiments do not exclude the possibility that one or more neutrinos are very slightly superluminal or that they have a very small tachyonic mass. Important bounds on the size of a hypothetical tachyonic neutrino mass term are set by lepton pair Čerenkov radiation (LPCR), that is, by the decay channelν→e+e-ν, which proceeds via a virtualZ0boson. Here, we use a Lorentz-invariant dispersion relation which leads to very tight constraints on the tachyonic mass of neutrinos; we also calculate decay and energy loss rates. A possible cutoff seen in the IceCube neutrino spectrum forEν>2 PeV, due to the potential onset of LPCR, is discussed.
37
Itoh, Naoki. "Neutrino Emission Processes in the Weinberg-Salam Theory". International Astronomical Union Colloquium 108 (1988): 434–35. http://dx.doi.org/10.1017/s025292110009429x.
Testo completoAbstract (sommario):
The neutrino emission processes play essential roles in stellar evolution as expemplified by the observations of the neutrinos from SN 1987a by the KAMIOKANDE-II and IMB experiments. Recently a very extensive study of the various neutrino emission processes based on the Weinberg-Salam theory has been completed by the present author and his collaborators. The neutrino emission processes calculated by the author’s group include pair, photo-, plasma, and bremsstrahlung neutrino processes. The neutrino energy loss rates due to pair, photo-, and plasma processes in the framework of the Weinberg-Salam theory are found to be substantially lower than the result obtained by Beaudet, Petrosian, and Salpeter. The reduction factor α is in the range 0.35 < α < 0.88 depending on the neutrino masses, density, and temperature. The ionic correlation effects play important roles in the bremsstrahlung neutrino process. The present author and his collaborators recently calculated the bremsstrahlung neutrino energy loss rate taking into account the ionic correlation effects in the crystalline lattice state as well as in the liquid metal state. They found that the ionic correlation effects suppress the bremsstrhlung neutrino energy loss typically by a factor 2-20. The present findings will bear great importance in neutrino astronomy.
38
Song, Cui-Ying, Tong Liu e Yun-Feng Wei. "Neutrinos and gravitational waves from magnetized neutrino-dominated accretion discs with magnetic coupling". Monthly Notices of the Royal Astronomical Society 494, n. 3 (9 aprile 2020): 3962–70. http://dx.doi.org/10.1093/mnras/staa932.
Testo completoAbstract (sommario):
ABSTRACT 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.
39
MORRISON, DOUGLAS R. O. "UPDATED REVIEW OF SOLAR MODELS AND SOLAR NEUTRINO EXPERIMENTS". International Journal of Modern Physics D 01, n. 02 (gennaio 1992): 281–302. http://dx.doi.org/10.1142/s0218271892000148.
Testo completoAbstract (sommario):
The Conventional Wisdom that there is a Solar Neutrino Problem and that New Physics is required, is examined. The various solar evolutionary models, (or SSM), are described and in particular the four new 1992 papers. While the evolutionary models are generally robust, there are important assumptions and uncertainties (screening, nuclear reaction rates, etc.) which mean that the errors cannot be small. Diffusion in the Sun is expected to be significant but so far there is no calculation which includes all types of diffusion, especially turbulent diffusion. The new and important helioseismological results are shown to to be in agreement with some of the SSM calculations. The experimental results are beginning to be not inconsistent with the SSM calculations. Kamiokande is consistent with SSM calculations except for one with rather small errors. The new GALLEX result is in agreement with all SSM calculations within 1.3 to 2 standard deviations. The 1990 SAGE I experiment is shown to have no evidence of solar neutrinos and is inconsistent with all SSM calculations and with GALLEX. However the new 1991 SAGE II experiment finds neutrino rates not inconsistent with SSM calculations. The Chlorine experiment is significantly below SSM calculations and is inconsistent with Kamiokande. In particular the Chlorine claim that there is a variation of the solar neutrino flux with the inverse of the sunspot activity, which shows a correlation of five standard deviation significance, is in contradiction with the results of the Kamiokande experiment which finds no variation of the solar neutrino flux with time. The overall conclusion is that there is no compelling evidence for a Solar Neutrino Problem or need for New Physics. However the neutrinos could still have masses and further experiments with higher statistics are essential as they are one of the rare ways of studying this low mass region. Thus the Solar Neutrino Problem is becoming a Neutrino Mass Quest.
40
Paar, N., T. Marketin, D. Vale e D. Vretenar. "Modeling nuclear weak-interaction processes with relativistic energy density functionals". International Journal of Modern Physics E 24, n. 09 (settembre 2015): 1541004. http://dx.doi.org/10.1142/s0218301315410049.
Testo completoAbstract (sommario):
Relativistic energy density functionals have become a standard framework for nuclear structure studies of ground state properties and collective excitations over the entire nuclide chart. In this paper, we review recent developments in modeling nuclear weak-interaction processes: Charge-exchange excitations and the role of isoscalar proton–neutron pairing, charged-current neutrino–nucleus reactions relevant for supernova evolution and neutrino detectors and calculation of β-decay rates for r-process nucleosynthesis.
41
Just, O., S. Goriely, H.-Th Janka, S. Nagataki e A. Bauswein. "Neutrino absorption and other physics dependencies in neutrino-cooled black hole accretion discs". Monthly Notices of the Royal Astronomical Society 509, n. 1 (8 ottobre 2021): 1377–412. http://dx.doi.org/10.1093/mnras/stab2861.
Testo completoAbstract (sommario):
ABSTRACT Black hole (BH) accretion discs formed in compact-object mergers or collapsars may be major sites of the rapid-neutron-capture (r-)process, but the conditions determining the electron fraction (Ye) remain uncertain given the complexity of neutrino transfer and angular-momentum transport. After discussing relevant weak-interaction regimes, we study the role of neutrino absorption for shaping Ye using an extensive set of simulations performed with two-moment neutrino transport and again without neutrino absorption. We vary the torus mass, BH mass and spin, and examine the impact of rest-mass and weak-magnetism corrections in the neutrino rates. We also test the dependence on the angular-momentum transport treatment by comparing axisymmetric models using the standard α-viscosity with viscous models assuming constant viscous length-scales (lt) and 3D magnetohydrodynamic (MHD) simulations. Finally, we discuss the nucleosynthesis yields and basic kilonova properties. We find that absorption pushes Ye towards ∼0.5 outside the torus, while inside increasing the equilibrium value $Y_\mathrm{ e}^{\mathrm{eq}}$ by ∼0.05–0.2. Correspondingly, a substantial ejecta fraction is pushed above Ye = 0.25, leading to a reduced lanthanide fraction and a brighter, earlier, and bluer kilonova than without absorption. More compact tori with higher neutrino optical depth, τ, tend to have lower $Y_\mathrm{ e}^{\mathrm{eq}}$ up to τ ∼ 1–10, above which absorption becomes strong enough to reverse this trend. Disc ejecta are less (more) neutron rich when employing an lt = const. viscosity (MHD treatment). The solar-like abundance pattern found for our MHD model marginally supports collapsar discs as major r-process sites, although a strong r-process may be limited to phases of high mass-infall rates, $\dot{M}\, \, \raise0.14em\rm{\gt }\lower0.28em\rm{\sim }\, \, 2\times 10^{-2}$ M⊙ s−1.
42
Abbasi, R., M. Ackermann, J. Adams, N. Aggarwal, J. A. Aguilar, M. Ahlers, J. M. Alameddine et al. "Constraints on Populations of Neutrino Sources from Searches in the Directions of IceCube Neutrino Alerts". Astrophysical Journal 951, n. 1 (1 luglio 2023): 45. http://dx.doi.org/10.3847/1538-4357/acd2ca.
Testo completoAbstract (sommario):
Abstract Beginning in 2016, the IceCube Neutrino Observatory has sent out alerts in real time containing the information of high-energy (E ≳ 100 TeV) neutrino candidate events with moderate to high (≳30%) probability of astrophysical origin. In this work, we use a recent catalog of such alert events, which, in addition to events announced in real time, includes events that were identified retroactively and covers the time period of 2011–2020. We also search for additional, lower-energy neutrinos from the arrival directions of these IceCube alerts. We show how performing such an analysis can constrain the contribution of rare populations of cosmic neutrino sources to the diffuse astrophysical neutrino flux. After searching for neutrino emission coincident with these alert events on various timescales, we find no significant evidence of either minute-scale or day-scale transient neutrino emission or of steady neutrino emission in the direction of these alert events. This study also shows how numerous a population of neutrino sources has to be to account for the complete astrophysical neutrino flux. Assuming that sources have the same luminosity, an E −2.5 neutrino spectrum, and number densities that follow star formation rates, the population of sources has to be more numerous than 7 × 10−9 Mpc−3. This number changes to 3 × 10−7 Mpc−3 if number densities instead have no cosmic evolution.
43
Itoh, Naoki. "Neutron Star Cooling: Criticical Test of Dense Matter Physics". Symposium - International Astronomical Union 125 (1987): 439–46. http://dx.doi.org/10.1017/s007418090016108x.
Testo completoAbstract (sommario):
Recent developments in the standard theory of neutron star cooling is critically reviewed. Emphasis is placed on the recent developments in the calculations of thermal conductivity and neutrino energy loss rates.
44
Slad, L. M. "Existing and expected manifestations of a new fundamental interaction". International Journal of Modern Physics E 30, n. 06 (giugno 2021): 2150052. http://dx.doi.org/10.1142/s021830132150052x.
Testo completoAbstract (sommario):
In this paper, a number of characteristics of the new fundamental interaction are described. The interaction is carried by a massless pseudoscalar boson and extends to at least the electron neutrino, proton and neutron. A substantiation of the existence of such an interaction is supported by an good agreement between the theoretical and experimental rates of all the five observed processes with solar neutrinos. A bright manifestation of the new interaction is expected in the observation that its contribution to the rate of splitting of a number of light stable nuclei by reactor antineutrinos is approximately six orders of magnitude greater than the contribution of electroweak interaction.
45
Chauhan, S., M. Sajjad Athar e S. K. Singh. "Neutrino-nucleus cross-sections at supernova neutrino energies". International Journal of Modern Physics E 26, n. 07 (luglio 2017): 1750047. http://dx.doi.org/10.1142/s0218301317500471.
Testo completoAbstract (sommario):
The inclusive neutrino/antineutrino-induced charged and neutral current reaction cross-sections in [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] in the energy region of supernova neutrinos/antineutrinos are studied. The calculations are performed in the local density approximation (LDA) taking into account the effects due to Pauli blocking, Fermi motion and the renormalization of weak transition strengths in the nuclear medium. The effect of Coulomb distortion of the lepton produced in the charged current reactions has also been included. The numerical results for the energy dependence of the cross-section [Formula: see text] as well as the flux averaged cross-section and event rates for the charged lepton production in the case of some supernova neutrino/antineutrino fluxes recently discussed in the literature have been presented. We have also given the flux-averaged angular and energy distributions of the charged leptons corresponding to these fluxes.
46
Panda, Papia, Monojit Ghosh e Rukmani Mohanta. "Determination of neutrino mass ordering from Supernova neutrinos with T2HK and DUNE". Journal of Cosmology and Astroparticle Physics 2023, n. 10 (1 ottobre 2023): 033. http://dx.doi.org/10.1088/1475-7516/2023/10/033.
Testo completoAbstract (sommario):
Abstract In this paper, we study the possibility of determining the neutrino mass ordering from the future supernova neutrino events at the DUNE and T2HK detectors. We estimate the expected number of neutrino event rates from a future supernova explosion assuming Garching flux model corresponding to different processes that are responsible for detecting the supernova neutrinos at these detectors. We present our results in the form of χ2, as a function of supernova distance. For a systematic uncertainty of 5% in normalisation as well as energy calibration error, our results show that, the neutrino mass ordering can be determined at 5 σ C.L. if the supernova explosion occurs at a distance of 42.7 kpc for T2HK and at a distance of 15.2 kpc for DUNE. Our results also show that the sensitivity of DUNE and T2HK get affected by the systematic uncertainties for the smaller supernova distances. Further, we show that in both DUNE and T2HK, the sensitivity gets deteriorated to some extent due to presence of energy smearing of the neutrino events. This occurs because of the reconstruction of the neutrino energy from the energy-momentum measurement of the outgoing leptons at the detector.
47
Bednarek, W., e A. Śmiałkowski. "High-energy neutrinos from fast winds in novae". Monthly Notices of the Royal Astronomical Society 511, n. 3 (2 febbraio 2022): 3339–45. http://dx.doi.org/10.1093/mnras/stac243.
Testo completoAbstract (sommario):
ABSTRACT We discuss a scenario in which TeV neutrinos are produced during explosions of novae. It is argued that hadrons are accelerated to very high energies in the inner part of a nova wind, as a result of reconnection of the strong magnetic field of a white dwarf. Hadrons are expected to interact efficiently with a dense matter of the wind, either already during the acceleration process or during their advection with the equatorial wind. We calculate the neutrino spectra and estimate the muon neutrino event rates in the IceCube telescope, in the case of a few novae. In general, those event rates are unlikely to be detected with the present neutrino detectors. However, for a favourable location of the observer, some neutrino events might be detected not only from the class of novae recently detected in the GeV γ-rays by the Fermi-LAT (Large Area Telescope), but also from novae not detected in γ-rays. The GeV γ-ray emission observed from novae cannot originate in terms of the model discussed here, since protons are accelerated within a few stellar radii of the white dwarf, i.e. in the region in which GeV γ-rays are expected to be severely absorbed in the interactions with the radiation field and the matter of the wind.
48
Abbasi, R., M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, M. Ahrens, C. Alispach et al. "Search for High-energy Neutrinos from Ultraluminous Infrared Galaxies with IceCube". Astrophysical Journal 926, n. 1 (1 febbraio 2022): 59. http://dx.doi.org/10.3847/1538-4357/ac3cb6.
Testo completoAbstract (sommario):
Abstract Ultraluminous infrared galaxies (ULIRGs) have infrared luminosities L IR ≥ 1012 L ⊙, making them the most luminous objects in the infrared sky. These dusty objects are generally powered by starbursts with star formation rates that exceed 100 M ⊙ yr−1, possibly combined with a contribution from an active galactic nucleus. Such environments make ULIRGs plausible sources of astrophysical high-energy neutrinos, which can be observed by the IceCube Neutrino Observatory at the South Pole. We present a stacking search for high-energy neutrinos from a representative sample of 75 ULIRGs with redshift z ≤ 0.13 using 7.5 yr of IceCube data. The results are consistent with a background-only observation, yielding upper limits on the neutrino flux from these 75 ULIRGs. For an unbroken E −2.5 power-law spectrum, we report an upper limit on the stacked flux Φ ν μ + ν ¯ μ 90 % = 3.24 × 10 − 14 TeV − 1 cm − 2 s − 1 ( E / 10 TeV ) − 2.5 at 90% confidence level. In addition, we constrain the contribution of the ULIRG source population to the observed diffuse astrophysical neutrino flux as well as model predictions.
49
DUNCAN, F. A. "RESULTS FROM THE PURE D2O PHASE OF THE SUDBURY NEUTRINO OBSERVATORY". International Journal of Modern Physics A 18, n. 22 (10 settembre 2003): 3789–807. http://dx.doi.org/10.1142/s0217751x0301718x.
Testo completoAbstract (sommario):
The Sudbury Neutrino Observatory is a 1000 T D2O Cerenkov detector that is sensitive to 8 B and hep solar neutrinos. Both Charged Current and Neutral Current interaction rates on deuterons as well as the Elastic Scattering interaction rate on electrons can be measured simultaneously. Assuming an undistorted 8 B neutrino spectrum, the total flux measured with the NC reaction is [Formula: see text], which is consistent with solar models. The νe component of the 8 B solar flux is [Formula: see text] for a kinetic energy threshold of 5 MeV. The non-νe component is [Formula: see text], which is 5.3σ greater than zero, giving strong evidence for solar νe flavor transformation. The Day-Night Asymmetry for the Charged Current interaction is [Formula: see text]. If the total flux of active neutrinos is additionally constrained to have no asymmetry, the νe asymmetry is found to be [Formula: see text]. Combined with other solar neutrino data, a global MSW oscillation analysis strongly favors the Large Mixing Angle (LMA) solution.
50
Lau, Rita. "Sensitivity studies on the thermal beta+ decay and thermal neutrino decay rates in the one-zone X-ray burst model". Monthly Notices of the Royal Astronomical Society 498, n. 2 (12 settembre 2020): 2697–702. http://dx.doi.org/10.1093/mnras/staa2484.
Testo completoAbstract (sommario):
ABSTRACT We investigated how the thermal beta+ decay rates and their corresponding neutrino energy loss rates affect the properties of X-ray bursts. Previous studies carried out showed how the beta+ decay rates alone affect the properties of X-ray bursts. Here, we performed the sensitivity studies on neutrino energy loss rates and their impact on X-ray bursts. Furthermore, all the experimental beta+ decay rates related to X-ray bursts were measured. However, the temperature of X-ray bursts can be as high as 1.5 GK. Thus, at such a high temperature, the nuclei can be in excited states due to thermal effects. Experiments cannot directly measure the thermal beta decay rates and thermal neutrino loss rates. We performed sensitivity tests on the thermal beta+ decay rates and their thermal neutrino losses in one-zone X-ray burst models in different ignition conditions. We discovered that beta decays due to thermal effects do affect the light curves in some ignition conditions. The thermal beta decay rates of 68Se also have major effects on the final abundances in most circumstances. We further found that a neutrino energy loss rate of 64Ga has noticeable effects on the light curves of X-ray bursts in general.