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detecting and studying galactic gamma-ray sources emitting very-high energy photons sheds light on the acceleration and propagation of cosmic rays presumably created in these sources. currently, there are few sources emitting photons with energies exceeding 100 tev. in this work we revisit the unidentified source mgro j1908+06, initially detected by milagro, using an updated h.e.s.s. dataset and analysis pipeline. the vicinity of the source contains a supernova remnant and pulsars as well as molecular clouds. this makes the identification of the primary source(s) of galactic cosmic rays as well as the nature of the gamma-ray emission challenging, especially in light of the recent hawc and lhaaso detection of the high energy tail of its spectrum. exploiting the better angular resolution as compared to particle detectors, we investigate the morphology of the source as well as its spectral properties. | revisiting the pevatron candidate mgro j1908+06 with an updated h.e.s.s. analysis |
supernovae chemically enrich their environments, drive future generations of star formation, and can accelerate particles up to the knee of the cosmic-ray spectrum. supernovae are inherently asymmetric processes, and the degree of asymmetry is determined by the explosion and the internal structure of the progenitor star. detailed studies of supernovae and their remnants can provide clues to the explosion physics and progenitor evolution by: (1) detecting trace elements which are formed via asymmetric neutrino emission during the explosion; (2): measuring bulk asymmetries in the velocity of differing layers of ejecta; and (3): probing the mass loss properties of the progenitor. high spectral resolution optical and nir studies of supernovae and their remnants partially address these questions, providing important diagnostics which allow for a reconstruction of the dynamics of the highest density ejecta. however, in most cases, ejecta in supernova remnants (and some supernovae) are brightest in x-rays. ccd resolution studies of supernova remnants can provide insight into the bulk properties of supernovae, but ccds lack the resolution to detect emission from trace elements and, importantly, are generally unable to measure bulk velocities of the ejecta. the line emission mapper is a proposed nasa probe class misssion which will map the properties of supernovae and their remnants in high spectral resolution. two ev microcalorimeter resolution will enable the reconstruction of explosion physics in both core-collapse and type ia supernova remnants in our galaxy and the local group. the high spectral resolution will measure bulk ejecta velocities, as well as detect trace elements which can provide clues as to the explosion mechanism. lem will allow for tomographic reconstruction of supernova remnants, probing the dynamics of ejecta and relating them back to supernova explosion models. we present specific examples of lem observations of galactic and extragalactic supernova remnants, and discuss how these studies with lem will address the role of supernovae in chemical enrichment and feedback within their ecosystems. | dissecting the energetics of supernovae at high spectral resolution: lem studies of supernovae and supernova remnants |
x-ray binaries are long-standing source candidates of galactic cosmic rays and neutrinos. the compact object in a binary system can be the site for cosmic-ray acceleration, while high-energy neutrinos can be produced by the interactions of cosmic rays in the jet of the compact object, the stellar wind, or the atmosphere of the companion star. we report a time-dependent study of high-energy neutrinos from x-ray binaries with icecube using 7.5 years of muon neutrino data and x-ray observations. in the absence of significant correlation, we report upper limits on the neutrino fluxes from these sources and provide a comparison with theoretical predictions. | searching for time-dependent high-energy neutrino emission from x-ray binaries with icecube |
ixpe has begun its first year of observations that will measure the linear polarization of energetic cosmic phenomena. this talk will discuss prospects for ixpe observations of selected radio-loud active galactic nuclei with sufficiently strong x-ray emission. during year 1, cen a and a number of quasars and bl lac objects are expected to be observed with ixpe, alongside x-ray spectral determinations from swift, nustar, and xmm-newton data, optical and uv flux measurements with the swift uvot, optical and millimeter-wave flux and polarization observations with ground-based telescopes, and gamma-ray flux and continuum spectra obtained from the fermi lat and atmospheric cherenkov detectors. the polarization observations will strongly constrain the dominant particle acceleration mechanism in the relativistic jets of blazars and radio galaxies. for blazars with relatively flat x-ray spectra, the polarization can potentially determine the x-ray emission process. community involvement with multi-wavelength observations is welcome. if approved, a future guest investigator program will provide opportunities for the members of the community to devise and carry out their own programs. | observations of blazars and radio galaxies with ixpe |
we summarise observations and our current understanding of the interstellar medium (ism) in galaxies, which mainly consists of three phases: cold atomic or molecular gas and clouds, warm neutral or ionised gas, and hot ionised gas. these three gas phases form thermally stable states, while disturbances are caused by gravitation and stellar feedback in form of photons and shocks in stellar winds and supernovae. hot plasma is mainly found in stellar bubbles, superbubbles, and galactic outflows/fountains and is often dynamically unstable and is over-pressurised. in addition, in galactic nuclear regions, accretion onto the supermassive black hole causes enhanced star formation, outflows, additional heating, and acceleration of cosmic rays. | diffuse hot plasma in the interstellar medium and galactic outflows |
ixpe has completed its first year of measurements of the linear polarization of energetic cosmic phenomena. this talk will discuss ixpe observations of selected radio-loud active galactic nuclei (agn) with high x-ray fluxes and strong and variable optical polarization (blazars). during the first year of operation ixpe observed a number of agn, which belong to both sub-classes of blazars, bl lac objects and quasars. observations with swift, nustar, xmm-newton, and integral performed along with ixpe measurements have been used to construct spectral energy distributions of the ixpe blazars over wide x-ray energy ranges. polarization data at optical, infra-red, and millimeter wavelengths have been obtained simultaneously with ixpe observations. such multi-wavelength data have provided constraints on the dominant particle acceleration mechanisms in relativistic jets of high synchrotron peak bl lac objects, while upper limits to the degree of x-ray polarization in low synchrotron peak blazars allow us to exclude some mechanisms for the x-ray production. | observations and modeling of blazars with the imaging x-ray polarimetry explorer (ixpe) |
astrophysical collisionless shocks play a central role in magnetic field amplification, plasma heating, and acceleration of galactic cosmic rays. a fundamental open question is what are the mechanisms that control the energy partition between ions and electrons downstream of the shock. observations of high mach number shocks have shown that te/ti >= 0.1, indicating that electrons acquire significantly more energy than that corresponding to simple thermalization of their initial kinetic energy. in this work we use 3d particle-in-cell simulations to investigate the electron and ion heating mechanisms in high mach number collisionless shocks, and find that te/ti is dictated by the nonlinear interplay between the ion current-filamentation and the drift-kink electromagnetic instabilities. the simulations yield temperature ratios compatible with astrophysical observations as well as with recent laser-produced collisionless shock experiments. | electron and ion thermalization in collisionless shocks |
recent studies show the importance of feedback in the evolution of the star formation rate in the universe. however, the nature and physics of the feedback are still pressing questions. radio continuum observations can provide unique dust-unbiased tracers of massive star formation and of the interstellar medium (ism) and hence are ideal to address the regulation of star formation in galaxies. our multi-frequency and multi-resolution radio surveys in nearby galaxies enable us to trace various phases of star formation and dissect the thermal and nonthermal ism in galaxies. mapping the cosmic ray electron energy index and magnetic field strength, we have found observational evidence that massive star formation significantly affects the energy balance in the ism through the injection and acceleration of cosmic rays and the amplification of magnetic fields. how the next generation of stars could form in such a magnetized and turbulent ism will be addressed in our 'evla cloud-scale survey of the local group galaxy m33' and in forthcoming surveys with the ska. | unveiling the physics of star formation and feedback in galaxies |
there are approximately (2-4)·1011 stars in the galaxy. many of these stars produce stellar flares, that is, they are active stars. it is known that our sun accelerates charged particles during powerful solar flares. if solar and stellar flares are compared, one can find many common features in these phenomena, and it is generally assumed that the underlying mechanism in solar and stellar flares is the same. to explain the experimental data on cosmic rays obtained recently using balloons and space experiments, the existence of cosmic ray sources near the solar system is required. in the present article, we discuss briefly some cosmic ray experimental data that can be explained if sources of cosmic rays exist near the solar system. we consider active dwarf stars as cosmic ray sources (in addition to supernova remnants). these stars constitute the main stellar population in the galaxy and generate powerful stellar flares, which are much more powerful than solar ones (up to 107 times). this suggestion enables to understand many features observed in cosmic rays over the past 20 years. in particular, the explanation of the positron excess is given in the frame of the known mechanisms without attracting dark matter. | why are new sources of cosmic rays nearby the solar system needed? |
one of the major scientific objectives of the future cherenkov telescope array (cta) observatory is the search for galactic pevatrons. galactic pevatrons are cosmic-ray factories able to accelerate nuclei at least up to 1 pev energies and beyond up to the knee feature seen at around 3 pev in the spectrum of cosmic rays. future cta will perform a survey of the galactic plane (cta gps) at tev energies with unprecedented sensitivity, allowing vhe gamma-ray measurements well beyond 100 tev. the determination of efficient criteria to identify pevatron candidates during the survey is essential in order to trigger further deep observations. here, we present results from a study based on simulations to investigate the possibility of detecting pevatrons within the cta gps. the outcome of the study is a spectral cutoff detection map that provide relations between spectral parameters and cutoff detection probabilities of pevatron sources. a selection criteria to determine potential pevatron sources during the cta gps is deduced. finally our results are applied to a synthetic population of young supernovae remnants as galactic pevatrons candidates, with the aim to estimate the expected number of detected pevatrons in the cta gps. | searching for pevatrons with cta |
the non-resonant (bell) streaming instability driven by energetic particles is crucial for producing amplified magnetic fields that are key to the acceleration of cosmic rays (crs) in supernova remnants, around galactic and extra-galactic cr sources, and for the cr transport. we present a covariant theory for the saturation of the bell instability, substantiated by self-consistent kinetic simulations, that can be applied to arbitrary cr distributions and discuss its implications in several heliospheric and astrophysical contexts. | the saturation of the bell instability and its implications for cosmic ray acceleration and transport |
recent measurements of primary and secondary cr spectra, their arrival directions, and our improved knowledge of the magnetic field geometry around the heliosphere allow us to set a bound on the distance beyond which a puzzling 10-tev "bump" cannot originate. the sharpness of the spectral breaks associated with the bump, the abrupt change of the cr intensity across the local magnetic equator ($90^{\circ}$ pitch angle), and the similarity between the primary and secondary cr spectral patterns point to a local reacceleration of the bump particles out of the background crs. we argue that a nearby shock may generate such a bump by increasing the rigidity of the preexisting crs below 50 tv by a mere factor of ~1.5. reaccelerated particles below ~0.5 tv are convected with the interstellar medium flow and do not reach the sun, thus creating the bump. this single universal process is responsible for the observed spectra of all cr species in the rigidity range below 100 tv. we propose that one viable candidate is the system of shocks associated with epsilon eridani star at 3.2 pc of the sun, which is well aligned with the direction of the local magnetic field. other shocks, such as old supernova shells, may produce a similar effect. we provide a simple formula that reproduces the spectra of all cr species with only three parameters uniquely derived from the cr proton data. we show how our formalism predicts helium and carbon spectra and the b/c ratio. | on why the 10-tev cosmic ray bump originates in the local interstellar medium |
non-thermal emission from relativistic electrons gives insight into the strength and morphology of intra-cluster magnetic fields, as well as providing powerful tracers of structure formation shocks. emission caused by cosmic ray (cr) protons on the other hand still challenges current observations and is therefore testing models of proton acceleration at intra-cluster shocks. large-scale simulations including the effects of crs have been difficult to achieve and have been mainly reduced to simulating an overall energy budget, or tracing cr populations in post-processing of simulation output and has often been done for either protons or electrons. we use an efficient on-the-fly fokker-planck solver to evolve distributions of cr protons and electrons within every resolution element of our simulation. the solver accounts for cr acceleration at intra-cluster shocks, based on results of recent pic simulations, re-acceleration due to shocks and mhd turbulence, adiabatic changes and radiative losses of electrons. we apply this model to zoom simulations of galaxy clusters, recently used to show the evolution of the small-scale turbulent dynamo on cluster scales. for these simulations we use a spectral resolution of 48 bins over 6 orders of magnitude in momentum for electrons and 12 bins over 6 orders of magnitude in momentum for protons. we present preliminary results about a possible formation mechanism for wrong way radio relics in our simulation. | galaxy cluster simulations with a spectral cosmic ray model -- "wrong way" radio relics |
starburst galaxies undergo intense episodes of star formation. in these galaxies, gas is ejected into the surroundings in the form of strong winds, produced by the combined effect of numerous supernova explosions. when these winds interact with the intergalactic medium, they give rise to strong shocks that are capable of accelerating cosmic rays. the radiation from these rays in radio wavelengths is generated by synchrotron mechanism and can be detected when the galaxies are seen "edge-on" (i.e., its inclination is ∼90° with the line of sight). in this work, we investigate a sub-sample of edge-on galaxies in the meerkat 1.28 ghz atlas of southern sources in the iras revised bright galaxy sample. to carry out an analysis of individual galaxies that allows us to find radio emission outside the galactic disk attributable to the presence of the wind, a software was developed and tested, which we detail in this work. we present here the results obtained using this software for a sub-group of galaxies that have been studied in the past using low-resolution observations, and we compare both results. | preliminary results of a search for radio halos in starburst galaxies |
in this paper, we review recent and ongoing work by our group on numerical simulations of relativistic jets. relativistic outflows in astrophysics are related to dilute, high energy plasmas, with physical conditions out of the reach of current laboratory capabilities. simulations are thus imperative for the study of these objects. we present a number of such scenarios that have been studied by our group at the universitat de valència. in particular, we have focused on the evolution of extragalactic outflows through galactic and intergalactic environments, deceleration by interaction with stars or clouds or the propagation of jets in x-ray binaries and interaction with stellar winds from massive companions. all also share their role as particle acceleration sites and production of non-thermal radiation throughout the electromagnetic spectrum. therefore, our work is not only aimed at understanding the impact of outflows on their environments and thus their role in galaxy and cluster evolution, but also the nature and capabilities of these sites as generators of high- and very-high-energy radiation and cosmic rays. | numerical simulations of relativistic jets |
although fanaroff-riley type 0 (fr 0) radio galaxies are known to be the most numerous jet population in the local universe, they are much less explored than the well-established class of fr type i (fr i) and fr type ii galaxies due to their intrinsic weakness. observationally, their nuclear radio, optical, and x-ray properties are comparable to the nuclear environment of fr is. the recent detection of two fr 0s in the high-energy band suggests that, like in fr is, charged particles are accelerated there to energies that enable gamma-ray production. up to now, only the lack of extended radio emission from fr 0s distinguishes them from fr is. by comparing the spectral energy distribution of fr 0s with that of fr is and in particular with that of m87 as a well-studied reference source of the fr i population, we find the broadband spectrum of fr 0 s exceptionally close to m87's quiet core emission. relying on that similarity, we apply a lepto-hadronic jet-accretion flow model to fr 0s. this model is able to explain the broadband spectral energy distribution, with parameters close to particle-field equipartition and matching all observational constraints. in this framework, fr 0s are multimessenger jet sources, with a nature and highly magnetized environment similar to those of the naked quiet core of fr is. | on the subparsec-scale core composition of fr 0 radio galaxies |
aims: in this work, we analysed new low frequency array observations of the mini halo in the cluster rbs 797, together with archival very large array observations and the recent chandra results. this cluster is known to host a powerful active galactic nucleus (agn) at its centre, with two pairs of jets propagating in orthogonal directions. recent x-ray observations have detected three pairs of shock fronts within 125 kpc from the cluster centre, connected with the activity of the central agn. our aim is to investigate the connection between the mini halo emission and the activity of the central source.methods: we have used different methods to separate the emission of the central source from the diffuse mini halo emission, and we have derived the radial spectral index trend of the mini halo.results: we find that the diffuse radio emission is elongated in different directions at 144 mhz (east-west) with respect to 1.4 ghz (north-south), tracing the orientation of the two pairs of jets. the mini halo emission is characterised by an average spectral index α = −1.02 ± 0.05. the spectral index profile of the mini halo shows a gradual flattening from the centre to the periphery. such a trend is unique among the mini halos studied to date, and resembles the spectral index trend typical of particles re-accelerated by shocks. however, the estimated contribution to the radio brightness profile coming from shock re-acceleration is found to be insufficient to account for the radial brightness profile of the mini halo.conclusions: we propose three scenarios that could explain the observed trend: (i) the agn-driven shocks are propagating onto an already existing mini halo, re-energising the electrons and leaving clear imprints in the mini halo spectral properties. we estimate that the polarisation induced by the shocks could be detected at 6 ghz and above; (ii) we could be witnessing turbulent re-acceleration in a high magnetic field cluster; and (iii) the mini halo could have a hadronic origin, in which the particles are injected by the central agn and the diffusion coefficient depends of the cosmic ray proton momentum. future observations in polarisation would be fundamental to understand the role of shocks and of the magnetic field. | shock imprints on the radio mini halo in rbs 797 |
observational evidence for the accelerated expansion of the universe requires dark energy for its explanation if general relativity is an accurate model of gravity. however, dark energy is a mysterious quantity and we do not know much about its nature so understanding dark energy is an exciting scientific challenge. cosmological dark energy models are fairly well tested in the low and high redshift parts of the universe. the highest of the low redshift, $z\sim2.3$, region is probed by baryon acoustic oscillation (bao) measurements and the only high redshift probe is the cosmic microwave background anisotropy which probes the $z\sim1100$ part of redshift space. in the intermediate redshift range $2.3 < z < 1100$ there are only a handful of observational probes and cosmological models are poorly tested in this region. in this thesis we constrain three pairs of general relativistic cosmological dark energy models using observational data which reach beyond the current bao limit. we use quasar x-ray and uv flux measurements, the current version of these data span $0.009 \leq z \leq 7.5413$. we have discovered that most of these data cannot be standardized using the proposed method. however, the lower redshift part, $z \lesssim 1.5-1.7$, of these data are standardizable and can be used to derive lower-$z$ cosmological constraints. another data set we use are gamma-ray burst measurements which span $0.3399 \leq z \leq 8.2$. cosmological constraints derived from these data are significantly weaker than, but consistent with, those obtained from better-established cosmological probes. we also study and standardize 78 reverberation-measured mg ii time-lag quasars in the redshift range $0.0033 \leq z \leq 1.89$ by using their radius-luminosity relation. we also study 118 reverberation-measured h$\beta$ time-lag quasars which span $0.0023 \leq z \leq 0.89$. | using quasar and gamma-ray burst measurements to constrain cosmological dark energy models |
odd radio circles (orcs) are mysterious rings of faint, diffuse emission recently discovered in radio surveys. some are potentially associated with galaxies, and proposed to be synchrotron emission from remnants of galactic outflows, which we call ogres. assuming that orcs arise from ogres, we discuss the broadband non-thermal emission and their evolution. we posit that a large amount of energy was ejected from the central galaxy in the past, creating an outgoing shock where cosmic rays are accelerated. from the observed spectral index and size of the orcs, we estimate the shock velocity and the injected energy. for reasonable values of the magnetic field and temperature of the ambient medium, we find that the ejected energy is required to be as high as ~10^60 erg to account for the observed radio power, suggesting that the energy source is active galactic nuclei. we also calculate the spectral energy distributions (seds) of the ogres and their evolution, including synchrotron, inverse compton (ic) and bremsstrahlung emission from electrons, and pion-decay emission from protons. younger ogres are expected to have seds with synchrotron and ic peaks in the soft x-ray and gamma-ray bands, respectively. in the future, they may be detectable at radio and higher frequencies, for example as ``odd x-ray circles''. in addition, infrared ic emission may be observable from some of the orcs found so far. future broadband observations of orcs should provide not only critical tests of this model, but may also offer unique probes of feedback effects on circumgalactic scales. | broadband non-thermal emission of odd radio circles induced by galactic outflow remnants and their evolution |
magnetic fields are involved in every astrophysical process on every scale:from planetary and stellar interiors to neutron stars, stellar wind bubbles and supernova remnants; from the interstellar medium in galactic disks, nuclei, spiral arms and halos to the intracluster and intergalactic media.they are involved in essentially every particle acceleration process and are thus fundamental to non-thermal physics in the universe.key questions include the origin of magnetic fields, their evolution over cosmic time, the amplification and decay processes that modify their strength, and their impact on other processes such as star formation and galaxy evolution.astrophysical plasmas provide a unique laboratory for testing magnetic dynamo theory. the study of magnetic fields requires observations that span the wavelength range from radio through infrared, optical, uv, x-ray, and gamma-ray. canada has an extremely strong record of research in cosmic magnetism, and has a significant leadership role in several ongoing and upcoming global programs.this white paper will review the science questions to be addressed in the study of cosmic magnetic fields and will describe the observational and theoretical opportunities and challenges afforded by the telescopes and modelling capabilities of today and tomorrow. | cosmic magnetism |
westerlund 1 (wd 1) is a massive stellar cluster located within the galaxy at a distance of ~5 kpc from the earth. the cluster is thought to be a site of significant galactic cosmic ray acceleration. further insight into this possibility can be gained through the study of gamma-ray emission from the cluster. the high energy stereoscopic system (hess) has detected an extended tev source coincident with wd 1 and now the fermi large area telescope (lat) has detected extended gev gamma-ray emission from the region. examining this data allows for a more precise understanding of the emission originating from wd 1 itself. we modeled the source as a 2-dimensional gaussian and, considering the region within 15º of the nominal position of wd 1, determined the maximum likelihood spectrum, position, and extension. it is clear that a significant, extended gev source is present and may be associated with the stellar cluster. we will additionally explore any energy dependence in the source's morphology to understand implications, particularly for the source association. continued examination of the emission originating from the wd 1 region will reveal details about the acceleration and composition of particles, both leptons and hadrons, originating in the region. | exploring evidence for cosmic ray acceleration in westerlund 1 |
i will review recent developments on the subject of acceleration and transport of galactic cosmic rays. recent observations, and the data collected by pamela and ams02 in particular, have revealed a number of unexpected features in the spectra of both primary and secondary cosmic rays. these findings seem to challenge the standard description of cosmic ray propagation through the galaxy and also impact our theories on the origin of these particles.i will discuss how at least some, if not all, of the presumed anomalies allow for an explanation based on non-linear effects associated with cr transport, and more generally what they suggest about the origin and propagation of galactic cosmic rays. | on the acceleration and transport of galactic cosmic rays |
this project focuses on the physics of the circumgalactic medium (cgm) and its role in galaxy evolution. the proposed work is motivated by evidence that the cgm holds the key to answering several of the outstanding central questions in galaxy formation, as well as by recent advances in galaxy formation simulations. the project will use a new generation of cosmological zoom-in simulations from the fire project, which include a comprehensive model for stellar feedback and have sufficient resolution to selfconsistently capture interactions between the ism and the cgm. the new simulations also include previously-neglected but important physical processes: magnetic fields, cosmic rays, and multi-channel agn feedback. in the first part, we will carry out a detailed analysis of the cosmic baryon cycle in the new simulations by identifying and tracking different types of gas flows based on their full history (inflows, outflows, recycling flows, ...). we will expand on previous work on the baryon cycle in three major ways: (i) a quantification of how the baryon cycle depends on the new magnetic field/cosmic ray/agn physics; (ii) a comprehensive analysis of the angular momentum evolution of gas in different channels and the implications for how galaxies assemble; and (iii) predictions for how abundance patterns trace different parts of the baryon cycle, which will enable observations to better constrain the feedback processes involved, including core collapse vs. type ia sne. in the second part, we will focus on the role of cgm virialization in driving critical transitions in galaxy evolution. recent work predicts that inner cgm virialization (icv) plays a key role in explaining multiple transitions experienced by galaxies around l*: (i) the emergence of large, long-lived galactic disks; (ii) the transition from bursty to steady star formation; (iii) the suppression of star formation-driven galactic winds around milky way-mass galaxies; and (iv) the accelerated growth of supermassive black holes and the onset of strong agn feedback. we will first use controlled simulations in which galaxy and cgm physical parameters can be varied independently to identify the causal mechanisms involved in these transitions, as well as to explicitly test the predictions of icv against competing theories. we will then use cosmological simulations to develop new statistical predictions necessary to test the proposed physical picture in observations. we will in particular predict how cgm properties relate to the formation of disk galaxies, the onset of agn feedback, the quenching of star formation, and the formation of ``red and dead'' massive ellipticals. this project will enable the interpretation of major discoveries made by several of nasa's observatories, including hst and chandra, about the cgm and galaxy evolution. the project will also produce predictions testable by future observations of galaxy evolution with jwst and roman, and of the hot cgm by future x-ray and cmb missions. | the physics of the cgm and its role in galaxy evolution |
the icecube collaboration (http://icecube.wisc.edu/) reports: icecube has performed a search for track-like muon neutrino events arriving from the direction of the type ii supernova sn 2023ixf in a time window of +/- 2 days from the ztf detection time (2023-05-17 07:45:07.200 to 2023-05-21 07:45:07.200) during which icecube was collecting good quality data. | sn 2023ixf: upper limits from a neutrino search with icecube |
in the dense supernova environment, neutrinos can undergo fast flavor conversions which depend on the large neutrino-neutrino interaction strength. it has been recently shown that both their presence and outcome can be affected when passing from the commonly used three neutrino species approach to the more general one with six species. here, we build up on a previous work performed on this topic and perform a numerical simulation of flavor evolution in both space and time, assuming six neutrino species. we find that the results presented in our previous work remain qualitatively the same even for flavor evolution in space and time. this emphasizes the need for going beyond the simplistic approximation with three species when studying fast flavor conversions. | supernova fast flavor conversions in 1 +1 d : influence of mu-tau neutrinos |
two-moment neutrino transport methods have been widely used for developing theoretical models of core-collapse supernovae (ccsn), since they substantially reduce the computational burden inherent in the multidimensional neutrino-radiation hydrodynamical simulations. the approximation, however, comes at a price; the detailed structure of angular distribution of neutrinos is sacrificed, that is the main drawback of this approach. in this paper, we develop a novel method by which to construct angular distributions of neutrinos from the zeroth and first angular moments. in our method, the angular distribution is expressed with two quadratic functions of the neutrino angle in a piecewise fashion. we determine the best parameters in the fitting function by comparing to the neutrino data in a spherically symmetric ccsn model with full boltzmann neutrino transport. we demonstrate the capability of our method by using our recent 2d ccsn model. we find that the essential features of the angular distributions can be well reconstructed, whereas the angular distributions of incoming neutrinos tend to have large errors that increase with flux factor (κ ). this issue originates from the insensitiveness of incoming neutrinos to κ , that is an intrinsic limitation in moment methods. based on the results of the demonstration, we assess the reliability of electron- neutrinos lepton number (eln)-crossing searches with the two-moment neutrino transport. this analysis is complementary to our [l. johns and h. nagakura arxiv:2104.04106] that scrutinizes the limitation of crossing searches with a few moments. we find that the systematic errors of angular distributions for incoming neutrinos lead to misjudgements of the crossing at κ ≳0.5 . this casts doubt on the results of eln-crossing searches based on two-moment methods in some previous studies. | constructing angular distributions of neutrinos in core-collapse supernovae from zeroth and first moments calibrated by full boltzmann neutrino transport |
light hypothetical particles with masses up to $\mathcal{o}(100)\ {\rm mev}$ can be produced in the core of supernovae. their subsequent decays to neutrinos can produce a flux component with higher energies than the standard flux. we study the impact of heavy neutral leptons, $z'$ bosons, in particular ${\rm u(1)}_{l_\mu-l_\tau}$ and ${\rm u(1)}_{b-l}$ gauge bosons, and majorons coupled to neutrinos flavor-dependently. we obtain new strong limits on these particles from no events of high-energy sn 1987a neutrinos and their future sensitivities from observations of galactic supernova neutrinos. | limits on heavy neutral leptons, $z'$ bosons and majorons from high-energy supernova neutrinos |
the gravitational waves (gw) from core-collapse supernovae (ccsn) have been proposed as a probe to investigate physical properties inside of the supernova. however, how to search and extract the gw signals from core-collapse supernovae remains an open question due to its complicated time-frequency structure. in this paper, we applied the ensemble empirical mode decomposition (eemd) method to decompose and reconstruct simulated gw data generated by magnetorotational mechanism and neutrino-driven mechanism within the advanced ligo, using the match score as the criterion for assessing the quality of the reconstruction. the results indicate that by decomposing the data, the sum of the first six intrinsic mode functions (imfs) can be used as the reconstructed waveform. to determine the probability that our reconstructed waveform corresponds to a real gw waveform, we calculated the false alarm probability of reconstruction (fapr). by setting the threshold of the match score to be 0.75, we obtained fapr of gw sources at a distance of 5 kpc and 10 kpc to be $1\times10^{-2}$ and $3\times10^{-2}$ respectively. if we normalize the maximum amplitude of the gw signal to $5\times10^{-21}$, the fapr at this threshold is $4\times10^{-3}$. furthermore, in our study, the reconstruction distance is not equivalent to the detection distance. when the strain of gw reaches $7 \times 10^{-21}$, and the match score threshold is set at 0.75, we can reconstruct gw waveform up to approximately 37 kpc. | waveform reconstruction of core-collapse supernovae gravitational-waves with ensemble empirical mode decomposition |
the cores of dense stars are a powerful laboratory for studying feebly-coupled particles such as axions. some of the strongest constraints on axionlike particles and their couplings to ordinary matter derive from considerations of stellar axion emission. in this work we study the radiation of axionlike particles from degenerate neutron star matter via a lepton-flavor-violating (lfv) coupling that leads to muon-electron conversion when an axion is emitted. we calculate the axion emission rate per unit volume (emissivity) and by comparing with the rate of neutrino emission, we infer upper limits on the lfv coupling that are at the level of $|g_{ae\mu}| \lesssim 10^{-6}$. for the hotter environment of a supernova, such as sn 1987a, the axion emission rate is enhanced and the limit is stronger, at the level of $|g_{ae\mu}| \lesssim 10^{-11}$, competitive with laboratory limits. interestingly, our derivation of the axion emissivity reveals that axion emission via the lfv coupling is suppressed relative to the familiar lepton-flavor-preserving channels by a factor of $t^2 e_{f,e}^2 / (m_\mu^2 - m_e^2)^2 \sim t^2/m_\mu^2$, which is responsible for the relatively weaker limits. | neutron star cooling with lepton-flavor-violating axions |
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 special 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 $10^{-15} \mu_b$ for a sterile neutrino in the $o(\rm{ev})$ mass range. | resonant spin-flavor precession of sterile neutrinos |
supernovae provide fascinating opportunities to study various particles and their interactions. among these there are neutrinos, axions, and other light weakly interacting particles, which play a significant role in our understanding of fundamental physics. in this study, the focus lies on the recent advancements made in characterizing axion emission from nuclear matter within the context of supernovae. the main production mechanisms for axions coupled with nucleons, bremsstrahlung and pion-axion conversion, are extensively discussed. these findings shed light on the behavior of axions in dense and hot nuclear matter, encountered in these extreme astrophysical environments. | axion emission from supernovae: a cheatsheet |
time of flight delay in the supernova neutrino signal offers a unique tool to set model-independent constraints on the absolute neutrino mass. the presence of a sharp time structure during a first emission phase, the so-called neutronization burst in the electron neutrino flavor time distribution, makes this channel a very powerful one. large liquid argon underground detectors will provide precision measurements of the time dependence of the electron neutrino fluxes. we derive here a new ν mass sensitivity attainable at the future dune far detector from a future supernova collapse in our galactic neighborhood, finding a sub-ev reach under favorable scenarios. these values are competitive with those expected for laboratory direct neutrino mass searches. | absolute ν mass measurement with the dune experiment |
in this article, we study the on-shell production of low-mass vector mediators from neutrino-antineutrino coalescence in the core of protoneutron stars. taking into account the radial dependence of the density, energy, and temperature inside the protoneutron star, we compute the neutrino-antineutrino interaction rate in the star interior in the well-motivated u (1 )lμ-lτ model. first, we determine the values of the coupling above which neutrino-antineutrino interactions dominate over the standard model neutrino-nucleon scattering. we argue that, although in this regime a redistribution of the neutrino energies might take place, making low-energy neutrinos more trapped, this only affects a small part of the neutrino population and it cannot be constrained with the sn 1987a data. thus, contrary to previous claims, the region of the parameter space where the u (1 )lμ-lτ model explains the discrepancy in the muon anomalous magnetic moment is not ruled out. we then focus on small gauge couplings, where the decay length of the new gauge boson is larger than the neutrino-nucleon mean free path, but still smaller than the size of protoneutron star. we show that in this regime, the on-shell production of a long-lived z' and its subsequent decay into neutrinos can significantly reduce the duration of the neutrino burst, probing values of the coupling below o (10-7) for mediator masses between 10 and 100 mev. this disfavors new areas of the parameter space of the u (1 )lμ-lτ model. | constraints from the duration of supernova neutrino burst on on-shell light gauge boson production by neutrinos |
we explore the energy and entropy transport as well as the lepton number variation induced from the mixing between electron and sterile neutrinos with kev mass in the supernova core. we develop a radial- and time-dependent treatment of the νs-νe mixing, by including ordinary matter effects, reconversions between sterile and electron antineutrinos, as well as the collisional production of sterile particles for the first time. the dynamical feedback due to the production of sterile particles on the composition and thermodynamic properties of the core only leads to major implications for the supernova physics for large mixing angles (sin2 2θ gtrsim 10-10). our findings suggest that a self-consistent appraisal of the electron-sterile conversion physics in the supernova core would relax the bounds on the sterile neutrino mixing parameters reported in the literature for sin2 2θ lesssim 10-6, leaving the (ms, sin2 2θ) parameter space relevant to dark matter searches unconstrained by supernovae. | lifting the core-collapse supernova bounds on kev-mass sterile neutrinos |
cosmology in the near future promises a measurement of the sum of neutrino masses ∑ mν, a fundamental standard model parameter, as well as substantially-improved constraints on the dark energy. we use the shape of the boss redshift-space galaxy power spectrum, in combination with cmb and supernova data, to constrain the neutrino masses and the dark energy. essential to this calculation are several recent advances in non-linear cosmological perturbation theory, including fast fourier transform methods, redshift space distortions, and scale-dependent growth. our 95% confidence upper bound ∑ mν < 180 mev degrades substantially to ∑ mν < 540 mev when the dark energy equation of state and its first derivative are also allowed to vary, representing a significant challenge to current constraints. we also study the impact of additional galaxy bias parameters, finding that a greater allowed range of scale-dependent bias only slightly shifts the preferred ∑ mν, weakens its upper bound by ≈ 20%, and has a negligible effect on the other cosmological parameters. | neutrino mass and dark energy constraints from redshift-space distortions |
heavy sterile neutrinos with masses script o(100) mev mixing with active neutrinos can be produced in the core of a collapsing supernova (sn). in order to avoid an excessive energy loss, shortening the observed duration of the sn 1987a neutrino burst, we show that the active-sterile neutrino mixing angle should satisfy sin2 θ lesssim 5 × 10-7. for a mixing with tau flavour, this bound is much stronger than the ones from laboratory searches. moreover, we show that in the viable parameter space the decay of such "heavy" sterile neutrinos in the sn envelope would lead to a very energetic flux of daughter active neutrinos; if not too far below current limits, this would be detectable in large underground neutrino observatories, like super-kamiokande, as a (slightly time-delayed) high-energy bump in the spectrum of a forthcoming galactic sn event. | heavy sterile neutrino emission in core-collapse supernovae: constraints and signatures |
context. modeling core-collapse supernovae (sne) with neutrino transport in three dimensions (3d) requires tremendous computing resources and some level of approximation. we present a first comparison study of core-collapse sne in 3d with different physics approximations and hydrodynamics codes.aims: the objective of this work is to assess the impact of the hydrodynamics code, approximations for the neutrino, gravity treatments, and rotation on the simulation of core-collapse sne in 3d.methods: we use four different hydrodynamics codes in this work (elephant, flash, fgr1, and sphynx) in combination with two different neutrino treatments, the isotropic diffusion source approximation (idsa) and two-moment m1, and three different gravity treatments (newtonian, 1d general relativity correction, and full general relativity). additional parameters discussed in this study are the inclusion of neutrino-electron scattering via a parametrized deleptonization and the influence of rotation.results: the four codes compared in this work include eulerian and fully lagrangian (smoothed particle hydrodynamics) codes for the first time. they show agreement in the overall evolution of the collapse phase and early post-bounce within the range of 10% (20% in some cases). the comparison of the different neutrino treatments highlights the need to further investigate the antineutrino luminosities in idsa, which tend to be relatively high. we also demonstrate the requirement for a more detailed heavy-lepton neutrino leakage. when comparing with a full general relativity code, including an m1 transport method, we confirm the influence of neutrino-electron scattering during the collapse phase, which is adequately captured by the parametrized deleptonization scheme. also, the effective general relativistic potential reproduces the overall dynamic evolution correctly in all newtonian codes. additionally, we verify that rotation aids the shock expansion and estimate the overall angular momentum losses for each code in rotating scenarios. | core-collapse supernovae in the hall of mirrors. a three-dimensional code-comparison project |
future large liquid-scintillator detectors can be implemented to observe neutrinos from a core-collapse supernova in our galaxy in various reaction channels: (1) the inverse beta decay ν¯ e+p →n +e+ , (2) the elastic neutrino-proton scattering ν +p →ν +p , (3) the elastic neutrino-electron scattering ν +e-→ν +e- , (4) the charged-current νe interaction νe+12c →e-+12n, (5) the charged-current ν¯ e interaction ν¯ e+12c →e++12b, and (6) the neutral-current interaction ν +12c →ν +12c* the less abundant 13c atoms in the liquid scintillator are also considered as a target, and both the charged-current interaction νe+13c →e-+13n and the neutral-current interaction ν +13c →ν +13c* are taken into account. in this work, we show for the first time that a global analysis of all these channels at a single liquid-scintillator detector, such as jiangmen underground neutrino observatory, is very important to test the average-energy hierarchy of supernova neutrinos and how the total energy is partitioned among neutrino flavors. in addition, the dominant channels for reconstructing neutrino spectra and the impact of other channels are discussed in great detail. | getting the most from the detection of galactic supernova neutrinos in future large liquid-scintillator detectors |
in the late stages of nuclear burning for massive stars (m > 8 m⊙), the production of neutrino-antineutrino pairs through various processes becomes the dominant stellar cooling mechanism. as the star evolves, the energy of these neutrinos increases and in the days preceding the supernova a significant fraction of emitted electron anti-neutrinos exceeds the energy threshold for inverse beta decay on free hydrogen. this is the golden channel for liquid scintillator detectors because the coincidence signature allows for significant reductions in background signals. we find that the kiloton-scale liquid scintillator detector kamland can detect these pre-supernova neutrinos from a star with a mass of 25 m⊙ at a distance less than 690 pc with 3σ significance before the supernova. this limit is dependent on the neutrino mass ordering and background levels. kamland takes data continuously and can provide a supernova alert to the community. | kamland sensitivity to neutrinos from pre-supernova stars |
the mixing of active neutrinos with their sterile counterparts with kev mass is known to have a potentially major impact on the energy loss from the supernova core. by relying on a set of three static hydrodynamical backgrounds mimicking the early accretion phase and the kelvin-helmoltz cooling phase of a supernova, we develop the first self-consistent, radial- and time-dependent treatment of νs-ντ mixing in the dense stellar core. we follow the flavor evolution by including ordinary matter effects, collisional production of sterile neutrinos, as well as reconversions of sterile states into active ones. the dynamical feedback of the sterile neutrino production on the matter background leads to the development of a ντ-bar nuτ asymmetry (yντ) that grows in time until it reaches a value larger than 0.15. our results hint towards significant implications for the supernova physics, and call for a self-consistent modeling of the sterile neutrino transport in the supernova core to constrain the mixing parameters of sterile neutrinos. | tau lepton asymmetry by sterile neutrino emission—moving beyond one-zone supernova models |
a large-scale neutrino observatory based on water-based liquid scintillator (wbls) will be excellently suited for a measurement of the diffuse supernova neutrino background (dsnb). the wbls technique offers high signal efficiency and effective suppression of the otherwise overwhelming background from neutral-current interactions of atmospheric neutrinos. to illustrate this, we investigate the dsnb sensitivity for two configurations of the future theia detector by developing the expected signal and background rejection efficiencies along a full analysis chain. based on a statistical analysis of the remaining signal and background rates, we find that a rather moderate exposure of 190 kt .yrs will be sufficient to claim a (5 σ ) discovery of the faint dsnb signal for standard model assumptions. we conclude that, in comparison with other experimental techniques, wbls offers the highest signal efficiency of more than 80% and best signal significance over background. | detecting the diffuse supernova neutrino background in the future water-based liquid scintillator detector theia |
in modern analysis pipelines, einstein-boltzmann solvers (ebss) are an invaluable tool for obtaining cmb and matter power spectra. to significantly accelerate the computation of these observables, the cosmicnet strategy is to replace the usual bottleneck of an ebs, which is the integration of a system of differential equations for linear cosmological perturbations, by trained neural networks. this strategy offers several advantages compared to the direct emulation of the final observables, including very small networks that are easy to train in high-dimensional parameter spaces, and which do not depend by construction on primordial spectrum parameters nor observation-related quantities such as selection functions. in this second cosmicnet paper, we present a more efficient set of networks that are already trained for extended cosmologies beyond λcdm, with massive neutrinos, extra relativistic degrees of freedom, spatial curvature, and dynamical dark energy. we publicly release a new branch of the class code, called classnet, which automatically uses networks within a region of trusted accuracy. we demonstrate the accuracy and performance of classnet by presenting several parameter inference runs from planck, bao and supernovae data, performed with classnet and the cobaya inference package. we have eliminated the perturbation module as a bottleneck of the ebs, with a speedup that is even more remarkable in extended cosmologies, where the usual approach would have been more expensive while the network's performance remains the same. we obtain a speedup factor of order 150 for the emulated perturbation module of class. for the whole code, this translates into an overall speedup factor of order 3 when computing cmb harmonic spectra (now dominated by the highly parallelizable and further optimizable line-of-sight integration), and of order 50 when computing matter power spectra (less than 0.1 seconds even in extended cosmologies). | cosmicnet ii: emulating extended cosmologies with efficient and accurate neural networks |
feebly interacting particles with masses with o (10 - 100 ) mev can be copiously produced by core-collapse supernovae (sne). in this paper we consider the case of mev-ish sterile neutrinos and dark photons mixed with ordinary neutrinos and photons, respectively. furthermore, both sterile neutrinos and dark photons may decay into positrons on their route to earth. such positrons would annihilate with electrons in the galactic medium and contribute to the photon flux in the 511 kev line. using the spectrometer on integral observation of this line improves the bounds on the mixing parameters for these particles by several orders of magnitude below what is already excluded by the sn 1987a energy-loss argument. | 511 kev line constraints on feebly interacting particles from supernovae |
we present a new method for neutrino-matter coupling in multi-dimensional radiation-hydrodynamic simulations of core-collapse supernovae (ccsne) with the full boltzmann neutrino transport. this development is motivated by the fact that accurate conservation of momentum is required for reliable numerical modelings of ccsn dynamics including a recoil of proto-neutron stars (pnss). the new method is built on a hybrid approach in which we use the energy-momentum tensor of neutrinos to compute the momentum feedback from neutrino to matter in the optically thick region while we employ the collision term in the optically thin region. in this method we utilize a general relativistic description of radiation-hydrodynamics with angular moments, which allows us to evaluate the momentum feedback from neutrino to matter without inconsistency with our boltzmann solver. we demonstrate that the new method substantially improves the accuracy of linear momentum conservation in our ccsn simulations under reasonable angular resolutions in momentum space, alleviating the difficulty in giving the diffusion limit precisely with the discrete ordinate (sn ) method. it is the first ever demonstration that the pns kick can be handled directly and properly in multi-dimensional radiation-hydrodynamic simulations with the full boltzmann neutrino transport. | three-dimensional boltzmann-hydro code for core-collapse in massive stars. iii. a new method for momentum feedback from neutrino to matter |
context. core-collapse supernovae (ccsne) are expected to emit gravitational wave signals that could be detected by current and future generation interferometers within the milky way and nearby galaxies. the stochastic nature of the signal arising from ccsne requires alternative detection methods to matched filtering.aims: we aim to show the potential of machine learning (ml) for multi-label classification of different ccsne simulated signals and noise transients using real data. we compared the performance of 1d and 2d convolutional neural networks (cnns) on single and multiple detector data. for the first time, we tested multi-label classification also with long short-term memory (lstm) networks.methods: we applied a search and classification procedure for ccsne signals, using an event trigger generator, the wavelet detection filter (wdf), coupled with ml. we used time series and time-frequency representations of the data as inputs to the ml models. to compute classification accuracies, we simultaneously injected, at detectable distance of 1 kpc, ccsn waveforms, obtained from recent hydrodynamical simulations of neutrino-driven core-collapse, onto interferometer noise from the o2 ligo and virgo science run.results: we compared the performance of the three models on single detector data. we then merged the output of the models for single detector classification of noise and astrophysical transients, obtaining overall accuracies for ligo (~99%) and (~80%) for virgo. we extended our analysis to the multi-detector case using triggers coincident among the three itfs and achieved an accuracy of ~98%. | lstm and cnn application for core-collapse supernova search in gravitational wave real data |
in this paper, we revisit the sn1987a neutrino data to see its constraints on flavor conversion. we are motivated by the fact that most works that analyze this data consider a specific conversion mechanism, such as the msw (mikheyev-smirnov-wolfenstein) effect, although flavor conversion is still an open question in supernovae due to the presence of neutrino-neutrino interactions. in our analysis, instead of considering a specific conversion mechanism, we let the electron antineutrino survival probability pe ¯e ¯ be a free parameter. we fit the data from kamiokande-ii, baksan, and imb detected spectrum with two classes of models: time-integrated and time-dependent. for the time-integrated model, it is not possible to put limits above 1 σ (68% confidence level) on the survival probability. the same happens for the time-dependent model when cooling is the only mechanism of antineutrino emission. however, for models considering an accretion phase, pe ¯e ¯∼0 is strongly rejected, showing a preference for the existence of an accretion component in the detected antineutrino flux, and a preference for normal mass ordering when only the msw is present. | sn1987a neutrino burst: limits on flavor conversion |
we suggest the future detection of neutrinos from a galactic core-collapse supernova can be used to infer the progenitor’s inner mass density structure. we present the results from 20 axisymmetric core-collapse supernova simulations performed with progenitors spanning initial masses in the range 11-30 {m}⊙ , and focus on their connections to the progenitor compactness. the compactness is a measure of the mass density profile of the progenitor core and recent investigations have suggested its salient connections to the outcomes of core collapse. our simulations confirm a correlation between the neutrinos emitted during the accretion phase and the progenitor’s compactness, and that the ratio of observed neutrino events during the first hundreds of milliseconds provides a promising handle on the progenitor’s inner structure. neutrino flavor mixing during the accretion phase remains a large source of uncertainty. | estimating the core compactness of massive stars with galactic supernova neutrinos |
the advent of gadolinium-loaded super-kamiokande (sk-gd) and of the soon-to-start juno liquid scintillator detector marks a substantial improvement in global sensitivity for the diffuse supernova neutrino background (dsnb). the present article reviews the detector properties most relevant for the dsnb searches in both experiments and estimates the expected signal and background levels. based on these inputs, we evaluate the sensitivity of both experiments individually and combined. using a simplified statistical approach, we find that both sk-gd and juno have the potential to reach >3σ evidence of the dsnb signal within 10 years of measurement. combination of their results is likely to enable a 5σ discovery of the dsnb signal within the next decade. | prospects for the detection of the diffuse supernova neutrino background with the experiments sk-gd and juno |
in the absence of high-statistics supernova neutrino measurements, estimates of the diffuse supernova neutrino background (dsnb) hinge on the precision of simulations of core-collapse supernovae. understanding the cooling phase of protoneutron star (pns) evolution (≳1 s after core bounce) is crucial, since approximately 50% of the energy liberated by neutrinos is emitted during the cooling phase. we model the cooling phase with a hybrid method by combining the neutrino emission predicted by 3d hydrodynamic simulations with several cooling-phase estimates, including a novel two-parameter correlation depending on the final baryonic pns mass and the time of shock revival. we find that the predicted dsnb event rate at super-kamiokande can vary by a factor of ∼2 - 3 depending on the cooling-phase treatment. we also find that except for one cooling estimate, the range in predicted dsnb events is largely driven by the uncertainty in the neutrino mean energy. with a good understanding of the late-time neutrino emission, more precise dsnb estimates can be made for the next generation of dsnb searches. | impact of late-time neutrino emission on the diffuse supernova neutrino background |
background: nuclear pasta, 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 study several possible pasta configurations, all of them minimal surface configurations, which are expected to appear in the mid-density regime of nuclear pasta, i.e., around 40% of the nuclear saturation density. in particular we are interested in the energy spectrum for different pasta configurations considered. method: employing the density functional theory approach, we calculate the binding energy of the different configurations for three values of the proton content xp=1 /10 ,1 /3 , and 1 /2 , by optimizing their periodic length. we study finite temperature effects and the impact of electron screening. results: nuclear pasta lowers the energy significantly compared to uniform matter, especially for xp≥1 /3 . however, the different configurations have very similar binding energies. for large proton content, xp≳1 /3 , the pasta configurations are very stable, for lower proton content temperatures of a few mev are enough for the transition to uniform matter. electron screening has a small influence on the binding energy of nuclear pasta, but increases its periodic length. conclusion: nuclear pasta in the mid-density regime lowers the energy of the matter for all proton fractions under study. it can survive even large temperatures of several mev. since various configurations have very similar energy, it is to expect that many configurations can coexist simultaneously already at small temperatures. | survey of nuclear pasta in the intermediate-density regime: shapes and energies |
neutrinos from a galactic core-collapse supernova will be measured by neutrino detectors minutes to days before an optical signal reaches earth. we present a novel calculation showing the ability of current and near-future neutrino detectors to make fast predictions of the progenitor distance and place constraints on the zero-age main sequence mass in order to inform the observing strategy for electromagnetic follow-up. we show that for typical galactic supernovae, the distance can be constrained with an uncertainty of $\sim$5\% using icecube or hyper-k and, furthermore, the zero-age main sequence mass can be constrained for extremal values of compactness. | measuring the distance and mass of galactic core-collapse supernovae using neutrinos |
neutron tagging in gadolinium-doped water may play a significant role in reducing backgrounds from atmospheric neutrinos in next generation proton-decay searches using megaton-scale water cherenkov detectors. similar techniques might also be useful in the detection of supernova neutrinos. accurate determination of neutron tagging efficiencies will require a detailed understanding of the number of neutrons produced by neutrino interactions in water as a function of momentum transferred. we propose the atmospheric neutrino neutron interaction experiment (annie), designed to measure the neutron yield of atmospheric neutrino interactions in gadolinium-doped water. an innovative aspect of the annie design is the use of precision timing to localize interaction vertices in the small fiducial volume of the detector. we propose to achieve this by using early production of lappds (large area picosecond photodetectors). this experiment will be a first application of these devices demonstrating their feasibility for water cherenkov neutrino detectors. | letter of intent: the accelerator neutrino neutron interaction experiment (annie) |
we investigate the precision with which the supernova neutrino spectra can be reconstructed in water cherenkov detectors, in particular the large scale hyper-kamiokande and super-kamiokande. to this aim, we consider quasi-thermal neutrino spectra modified by the mikheev-smirnov-wolfenstein effect for the case of normal ordering. we perform three 9 degrees of freedom likelihood analyses including first inverse-beta decay only, then the combination of inverse beta decay and elastic scattering on electrons and finally a third analysis that also includes neutral scattering neutrino-oxygen events. a tenth parameter is added in the analyses to account for the theoretical uncertainty on the neutral current neutrino-oxygen cross section. by assuming a 100% efficiency in hyper-kamiokande, we show that one can reconstruct the electron antineutrino average energy and pinching parameter with an accuracy of ~2% and ~7% percent respectively, while the antineutrino integrated luminosity can be pinned down at ~3% percent level. as for the muon and tau neutrinos, the average energy and the integrated luminosity can be measured with ~7% precision. these results represent a significant improvement with respect super-kamiokande, particularly for the pinching parameter defining the electron antineutrino spectra. as for electron neutrinos, the determination of the emission parameters requires the addition of supplementary detection channels. | what can we learn on supernova neutrino spectra with water cherenkov detectors? |
we study the multi-dimensional properties of neutrino transfer inside supernova cores by solving the boltzmann equations for neutrino distribution functions in genuinely six-dimensional phase space. adopting representative snapshots of the post-bounce core from other supernova simulations in three dimensions, we solve the temporal evolution to stationary states of neutrino distribution functions using our boltzmann solver. taking advantage of the multi-angle and multi-energy feature realized by the snmethod in our code, we reveal the genuine characteristics of spatially three-dimensional neutrino transfer, such as nonradial fluxes and nondiagonal eddington tensors. in addition, we assess the ray-by-ray approximation, turning off the lateral-transport terms in our code. we demonstrate that the ray-by-ray approximation tends to propagate fluctuations in thermodynamical states around the neutrino sphere along each radial ray and overestimate the variations between the neutrino distributions on different radial rays. we find that the difference in the densities and fluxes of neutrinos between the ray-by-ray approximation and the full boltzmann transport becomes ~20%, which is also the case for the local heating rate, whereas the volume-integrated heating rate in the boltzmann transport is found to be only slightly larger (~2%) than the counterpart in the ray-by-ray approximation due to cancellation among different rays. these results suggest that we should carefully assess the possible influences of various approximations in the neutrino transfer employed in current simulations of supernova dynamics. detailed information on the angle and energy moments of neutrino distribution functions will be profitable for the future development of numerical methods in neutrino-radiation hydrodynamics. | multi-dimensional features of neutrino transfer in core-collapse supernovae |
based on the recently formulated chiral radiation transport theory for left-handed neutrinos, we study the chiral transport of neutrinos near thermal equilibrium in core-collapse supernovae. we first compute the near-equilibrium solution of the chiral radiation transport equation under the relaxation time approximation, where the relaxation time is directly derived from the effective field theory of the weak interaction. by using such a solution, we systematically derive analytic expressions for the nonequilibrium corrections of the neutrino energy-momentum tensor and neutrino number current induced by magnetic fields via the neutrino absorption on nucleons. in particular, we find the nonequilibrium neutrino energy current proportional to the magnetic field. we also discuss its phenomenological consequences such as the possible relation to pulsar kicks. | magnetic field induced neutrino chiral transport near equilibrium |
in this review article, we discuss selected developments regarding the role of the equation of state in simulations of core-collapse supernovae. there are no first-principle calculations of the state of matter under supernova conditions since a wide range of conditions is covered, in terms of density, temperature, and isospin asymmetry. instead, model equation of state are commonly employed in supernova studies. these can be divided into regimes with intrinsically different degrees of freedom: heavy nuclei at low temperatures, inhomogeneous nuclear matter where light and heavy nuclei coexist together with unbound nucleons, and the transition to homogeneous matter at high densities and temperatures. in this article, we discuss each of these phases with particular view on their role in supernova simulations. | the state of matter in simulations of core-collapse supernovae—reflections and recent developments |
paleodetectors are a proposed experimental technique in which one would search for traces of recoiling nuclei in ancient minerals. natural minerals on earth are as old as o (1 ) gyr and, in many minerals, the damage tracks left by recoiling nuclei are also preserved for timescales long compared to 1 gyr once created. thus, even reading out relatively small target samples of order 100 g, paleodetectors would allow one to search for very rare events thanks to the large exposure, ɛ ∼100 g gyr =105 t yr . here, we explore the potential of paleodetectors to measure nuclear recoils induced by neutrinos from galactic core collapse supernovae. we find that they would not only allow for a direct measurement of the average core collapse supernova rate in the milky way, but would also contain information about the time dependence of the local supernova rate over the past ∼1 gyr . since the supernova rate is thought to be directly proportional to the star formation rate, such a measurement would provide a determination of the local star formation history. we investigate the sensitivity of paleodetectors to both a smooth time evolution and an enhancement of the core collapse supernova rate on relatively short timescales, as would be expected for a starburst period in the local group. | paleodetectors for galactic supernova neutrinos |
the detection of neutrinos from core-collapse supernovae may reveal important process features as well as neutrino properties. the detection of supernova neutrinos is one of the main science drivers for future kiloton-scale neutrino detectors based on liquid argon. here we show that for such detectors the intrinsically 3d readout in q-pix offers numerous advantages relative to a wire-based readout, such as higher reconstruction efficiency, lower energy threshold, considerably lower data rates, and potential pointing information. | enhanced low-energy supernova burst detection in large liquid argon time projection chambers enabled by q-pix |
the experimental searches for diffuse supernova neutrino background and proton decay in next-generation large liquid-scintillator (ls) detectors are competitive with and complementary to those in the water-cherenkov detectors. in this paper, we carry out a systematic study of the dominant background induced by atmospheric neutrinos via their neutral-current (nc) interactions with the 12c nuclei in the ls detectors. the atmospheric neutrino fluxes at the location of jiangmen underground neutrino observatory (juno) are used, as the juno detector is obviously a suitable representative for future ls detectors. then, we implement the sophisticated generators genie and nuwro to simulate the neutrino interactions with the carbon nuclei, and the package talys to deal with the deexcitations of final-state nuclei. finally, the event rates for the production of additional nucleons, γ 's, α 's, pions, and kaons are obtained and categorized, and the systematic uncertainty of the nc background represented by a variety of data-driven nuclear models is estimated. the implications of the nc background from atmospheric neutrinos for the detection of diffuse supernova neutrino background and proton decay are also discussed. | neutral-current background induced by atmospheric neutrinos at large liquid-scintillator detectors. i. model predictions |
in this work, for the first time in literature, we compare the predictions of non-minimally coupled natural and coleman-weinberg potentials in the $n_s-r$ plane against the constraints from the latest cosmological data in an extended $\lambda$cdm model where we include non-standard self-interactions among massive neutrinos, mediated by a heavy scalar or vector boson. for the inflationary potentials, we consider two different formulations in gravity that are non-minimally coupled to the scalar field of the inflaton: \textit{metric and palatini.} we only consider the self-interaction to be present among $\tau$-neutrinos and only at moderate strengths. this is because strong interactions among $\tau$-neutrinos, or any strength self-interaction among electron- and muon-neutrinos, as well as any strength flavor-universal interactions, are strongly disfavoured from particle physics experiments. in terms of cosmological data, we use the latest public cmb datasets from planck and bicep/keck collaborations, along with other data from cmb lensing, bao, rsd, and sne ia luminosity distance measurements. we find that there are some situations where predictions from the inflationary models are ruled out at more than 2$\sigma$ by the minimal $\lambda$cdm$+r$ model, but they are allowed in the self-interacting neutrino scenario. | first constraints on non-minimally coupled natural and coleman-weinberg inflation in the light of massive neutrino self-interactions and planck+bicep/keck |
neutrino propagation through a turbulent medium can be highly non-adiabatic leading to distinct signatures in the survival probabilities. a core-collapse supernova can be host to a number of hydrodynamic instabilities which occur behind the shockfront. such instabilities between the forward shock and a possible reverse shock can lead to cascades introducing turbulence in the associated matter profile, which can imprint itself in the neutrino signal. in this work, we consider realistic matter profiles and seed in the turbulence using a randomization scheme to study its effects on neutrino propagation in an effective two-flavor framework. in particular, we find that the double-dip feature, originally predicted in the neutrino spectra associated with forward and reverse shocks, can be completely washed away in the presence of turbulence, leading to total flavor depolarization. we also study the sensitivity of upcoming neutrino detectors - dune and hyper-kamiokande- to the power spectrum of turbulence to check for deviations from the usual kolmogorov ($5/3$) inverse power law. we find that while these experiments can effectively constrain the parameter space for the amplitude of the turbulence power spectra, they will only be mildly sensitive to the spectral index. | on probing turbulence in core-collapse supernovae in upcoming neutrino detectors |
in view of the great interest in liquid argon neutrino detectors, the 40ar(γ ,γ')40ar reaction was revisited to guide a calculation of the neutral current neutrino cross section at supernova energies. using the nuclear resonance fluorescence technique with a monoenergetic, 99% linearly polarized photon beam, we report a three-fold increase in magnetic dipole strength at around 10 mev in 40ar. based on shell-model calculations, and using the experimentally identified transitions, the neutral current neutrino cross sections for low-energy reactions on 40ar are calculated. | neutral-current neutrino cross section and expected supernova signals for 40ar from a three-fold increase in the magnetic dipole strength |
we develop an approach to chiral kinetic theories for electrons close to equilibrium and neutrinos away from equilibrium based on a systematic power counting scheme for different timescales of electromagnetic and weak interactions. under this framework, we derive electric and energy currents along magnetic fields induced by neutrino radiation in general nonequilibrium states. this may be regarded as an effective chiral magnetic effect (cme), which is present without a chiral chemical potential, unlike the conventional cme. we also consider the so-called gain region of core-collapse supernovae as an example and find that the effective cme enhanced by persistent neutrino emission in time is sufficiently large to lead to the inverse cascade of magnetic and fluid kinetic energies and observed magnitudes of pulsar kicks. our framework may also be applicable to other dense-matter systems involving nonequilibrium neutrinos. | effective chiral magnetic effect from neutrino radiation |
measuring precise all-flavor neutrino information from a supernova is crucial for understanding the core-collapse process as well as neutrino properties. we apply a chi-squared analysis for different detector setups to explore determination of νe spectral parameters. using a long-term two-dimensional core-collapse simulation with three time-varying spectral parameters, we generate mock data to examine the capabilities of the current super-kamiokande detector and compare the relative improvements that gadolinium, hyper-kamiokande, and dune would have. we show that in a realistic three spectral parameter framework, the addition of gadolinium to super-kamiokande allows for a qualitative improvement in νe determination. efficient neutron tagging will allow hyper-kamiokande to constrain spectral information more strongly in both the accretion and cooling phases. overall, significant improvements will be made by hyper-kamiokande and dune, allowing for much more precise determination of νe spectral parameters. | robust measurement of supernova νe spectra with future neutrino detectors |
we investigate correlated gravitational wave and neutrino signals from rotating core-collapse supernovae with simulations. using an improved mode identification procedure based on mode function matching, we show that a linear quadrupolar mode of the core produces a dual imprint on gravitational waves and neutrinos in the early post-bounce phase of the supernova. the angular harmonics of the neutrino emission are consistent with the mode energy around the neutrinospheres, which points to a mechanism for the imprint on neutrinos. thus, neutrinos carry information about the mode amplitude in the outer region of the core, whereas gravitational waves probe deeper in. we also find that the best-fit mode function has a frequency bounded above by ∼420 hz , and yet the mode's frequency in our simulations is ∼15 % higher, due to the use of newtonian hydrodynamics and a widely used pseudo-newtonian gravity approximation. this overestimation is particularly important for the analysis of gravitational wave detectability and asteroseismology, pointing to limitations of pseudo-newtonian approaches for these purposes, possibly even resulting in excitation of incorrect modes. in addition, mode frequency matching (as opposed to mode function matching) could be resulting in mode misidentification in recent work. lastly, we evaluate the prospects of a multimessenger detection of the mode using current technology. the detection of the imprint on neutrinos is most challenging, with a maximum detection distance of ∼1 kpc using the icecube neutrino observatory. the maximum distance for detecting the complementary gravitational wave imprint is ∼5 kpc using advanced ligo at design sensitivity. | multimessenger asteroseismology of core-collapse supernovae |
we investigate the influences of the nuclear composition on the weak interaction rates of heavy nuclei during the core collapse of massive stars. the nuclear abundances in nuclear statistical equilibrium (nse) are calculated by some equation of state (eos) models including in-medium effects on nuclear masses. we systematically examine the sensitivities of electron capture and neutrino-nucleus scattering on heavy nuclei to the nuclear shell effects and the single-nucleus approximation. we find that the washout of the shell effect at high temperatures brings significant change to weak rates by smoothing the nuclear abundance distribution: the electron capture rate decreases by ∼20 % in the early phase and increases by ∼40 % in the late phase at most, while the cross section for neutrino-nucleus scattering is reduced by ∼15 % . this is because the open-shell nuclei become abundant instead of those with closed neutron shells as the shell effects disappear. we also find that the single-nucleus description based on the average values leads to underestimations of weak rates. electron captures and neutrino coherent scattering on heavy nuclei are reduced by ∼80 % in the early phase and by ∼5 % in the late phase, respectively. these results indicate that nse like eos accounting for shell washout is indispensable for the reliable estimation of weak interaction rates in simulations of core-collapse supernovae. | dependence of weak interaction rates on the nuclear composition during stellar core collapse |
the zwicky transient facility (ztf) performs a systematic neutrino follow-up programme, searching for optical counterparts to high-energy neutrinos with dedicated target-of-opportunity (too) observations. since first light in march 2018, ztf has taken prompt observations for 24 high-quality neutrino alerts from the icecube neutrino observatory, with a median latency of 12.2 h from initial neutrino detection. from two of these campaigns, we have already reported tidal disruption event (tde) at 2019dsg and likely tde at 2019fdr as probable counterparts, suggesting that tdes contribute >7.8 per cent of the astrophysical neutrino flux. we here present the full results of our programme through to december 2021. no additional candidate neutrino sources were identified by our programme, allowing us to place the first constraints on the underlying optical luminosity function of astrophysical neutrino sources. transients with optical absolutes magnitudes brighter that -21 can contribute no more than 87 per cent of the total, while transients brighter than -22 can contribute no more than 58 per cent of the total, neglecting the effect of extinction and assuming they follow the star formation rate. these are the first observational constraints on the neutrino emission of bright populations such as superluminous supernovae. none of the neutrinos were coincident with bright optical agn flares comparable to that observed for txs 0506+056/ic170922a, with such optical blazar flares producing no more than 26 per cent of the total neutrino flux. we highlight the outlook for electromagnetic neutrino follow-up programmes, including the expected potential for the rubin observatory. | neutrino follow-up with the zwicky transient facility: results from the first 24 campaigns |
the detection of the high-energy (∼290 tev) neutrino coincident with the flaring blazar txs 0506+056, the first and only 3σ neutrino-source association to date, provides new, multimessenger tests of the weak equivalence principle (wep) and lorentz invariance. assuming that the flight time difference between the tev neutrino and gamma-ray photons from the blazar flare is mainly caused by the gravitational potential of the laniakea supercluster of galaxies, we show that the deviation from the wep for neutrinos and photons is conservatively constrained to have an accuracy of 10-6-10-7, which is 3-4 orders of magnitude better than previous results placed by mev neutrinos from supernova 1987a. in addition, we demonstrate that the association of the tev neutrino with the blazar flare sets limits on the energy scales of quantum gravity for both linear and quadratic violations of lorentz invariance (liv) to eqg,1 > 3.2 ×1015- 3.7 ×1016 gev and eqg,2 > 4.0 ×1010- 1.4 ×1011 gev. these improve previous limits on both linear and quadratic liv energy scales in neutrino propagation by 5-7 orders of magnitude. | multimessenger tests of einstein's weak equivalence principle and lorentz invariance with a high-energy neutrino from a flaring blazar |
building on the framework of zhang & shu [1,2], we develop a realizability-preserving method to simulate the transport of particles (fermions) through a background material using a two-moment model that evolves the angular moments of a phase space distribution function f. the two-moment model is closed using algebraic moment closures; e.g., as proposed by cernohorsky & bludman [3] and banach & larecki [4]. variations of this model have recently been used to simulate neutrino transport in nuclear astrophysics applications, including core-collapse supernovae and compact binary mergers. we employ the discontinuous galerkin (dg) method for spatial discretization (in part to capture the asymptotic diffusion limit of the model) combined with implicit-explicit (imex) time integration to stably bypass short timescales induced by frequent interactions between particles and the background. appropriate care is taken to ensure the method preserves strict algebraic bounds on the evolved moments (particle density and flux) as dictated by pauli's exclusion principle, which demands a bounded distribution function (i.e., f ∈ [ 0 , 1 ]). this realizability-preserving scheme combines a suitable cfl condition, a realizability-enforcing limiter, a closure procedure based on fermi-dirac statistics, and an imex scheme whose stages can be written as a convex combination of forward euler steps combined with a backward euler step. the imex scheme is formally only first-order accurate, but works well in the diffusion limit, and - without interactions with the background - reduces to the optimal second-order strong stability-preserving explicit runge-kutta scheme of shu & osher [5]. numerical results demonstrate the realizability-preserving properties of the scheme. we also demonstrate that the use of algebraic moment closures not based on fermi-dirac statistics can lead to unphysical moments in the context of fermion transport. | realizability-preserving dg-imex method for the two-moment model of fermion transport |
supernova neutrino boosted dark matter (sn ν bdm) and its afterglow effect have been shown to be a promising signature for beyond standard model (bsm) physics. the time-evolution feature of sn ν bdm allows for possibly direct inference of dm mass mχ, and results in significant background suppression with improving sensitivity. this paper extends the earlier study [y.-h. lin et al., phys. rev. lett. 130, 111002 (2023), 10.1103/physrevlett.130.111002] and provides a general framework for computing the sn ν bdm fluxes for a supernova that occurs at any location in our galaxy. a bsm u (1 )lμ-lτ model with its gauge boson coupling to both dm and the second and third generation of leptons is considered, which allows for both dm-ν and dm-e interactions. detailed analysis of the temporal profile, angular distribution, and energy spectrum of the sn ν bdm are performed. unique signatures in sn ν bdm allowing extraction of mχ and detail features that contain information of the underlying interaction type are discussed. expected sensitivities on the above new physics model from super-kamiokande, hyper-kamiokande, and dune detections of bdm events induced by the next galactic sn are derived and compared with the existing bounds. | signatures of afterglows from light dark matter boosted by supernova neutrinos in current and future large underground detectors |
we study the influence of density-dependent symmetry energy at high densities in simulations of core-collapse supernovae, black hole formation, and proto-neutron star cooling by extending the relativistic mean field (rmf) theory used for the shen equation-of-state (eos) table. we adopt the extended rmf theory to examine the density dependence of the symmetry energy with a small value of the slope parameter l, while the original properties of the symmetric nuclear matter are unchanged. in order to assess matter effects at high densities, we perform numerical simulations of gravitational collapse of massive stars adopting the eos table at high densities beyond 1014 g cm-3 with the small l value, which is in accord with the experimental and observational constraints, and compare them with the results obtained by using the shen eos. numerical results for 11.2 and 15 m ⊙ stars exhibit minor effects around the core bounce and in the following evolution for 200 ms. numerical results for 40 and 50 m ⊙ stars reveal a shorter duration toward the black hole formation with a smaller maximum mass for the small-l case. numerical simulations of proto-neutron star cooling over 10 s through neutrino emissions demonstrate increasing effects of the symmetry energy at high densities. neutrino cooling drastically proceeds in a relatively long timescale with high luminosities and average energies with the small symmetry energy. evolution toward the cold neutron star is affected because of the different behavior of neutron-rich matter, while supernova dynamics around core bounce remains similar in less neutron-rich environments. | influence of density dependence of symmetry energy in hot and dense matter for supernova simulations |
the hubble tension, known as a discrepancy between the local measurements vs. the cmb, sne and galaxy clustering fits of the hubble constant, the first measurement of the 21-centimeter high-redshift signal by edges, the high-redshift galaxy halo number densities and the measurements of the ionizing photon mean free path represent a great challenge for the concordance cosmology. we show that the nonsingular einstein-cartan cosmological model with the simple parametrization of torsion of spacetime (angular momentum of the universe) can substantially improve agreement with data. light majorana neutrinos are dominant source of the spin of matter coupled to torsion, while the heavy majorana neutrinos represent cold dark matter particles fulfilling the griest-kamionkowski unitarity bound. | einstein-cartan cosmology and the high-redshift universe |
we calculate the neutrino luminosity in an astrophysical scenario where dark matter is captured by a neutron star which eventually implodes to form a low mass black hole. the trojan horse scenario involves the collapse of a neutron star (ns) due to the accumulation of a critical amount of dark matter (dm) during its lifetime. as a result, a central disk forms out of the ejected material with a finite radial extension, density, temperature, and lepton fraction, producing fainter neutrino luminosities and colder associated spectra than found in a regular core-collapse supernova. the emitted gravitational wave (gw) signal from the imploding ns should be detectable at ultra-high $\gtrsim 0.1$ ghz frequencies. | neutrino signals from neutron star implosions to black holes |
the present article investigates the role of heavy nuclear clusters and weakly bound light nuclear clusters based on a newly developed equation of state for core collapse supernova studies. a novel approach is brought forward for the description of nuclear clusters, taking into account the quasiparticle approach and continuum correlations. it demonstrates that the commonly employed nuclear statistical equilibrium approach, based on noninteracting particles, for the description of light and heavy clusters becomes invalid for warm nuclear matter near the saturation density. this has important consequences for studies of core collapse supernovae. to this end, we implement this nuclear equation of state provided for arbitrary temperature, baryon density, and isospin asymmetry, to spherically symmetric core collapse supernova simulations to study the impact on the dynamics as well as on the neutrino emission. for the inclusion of a set of weak processes involving light clusters the rate expressions are derived, including medium modifications at the mean-field level. a substantial impact from the inclusion of a variety of weak reactions involving light clusters on the post bounce dynamics and on the neutrino emission could not be found. | medium modifications for light and heavy nuclear clusters in simulations of core collapse supernovae: impact on equation of state and weak interactions |
the impact of electron-capture (ec) cross sections for neutron-rich nuclei on the dynamics of core collapse during infall and early post-bounce is studied by performing spherically symmetric simulations in general relativity using a multigroup scheme for neutrino transport and full nuclear distributions in extended nuclear statistical equilibrium models. we thereby vary the prescription for ec rates on individual nuclei, the nuclear interaction for the equation of state, the mass model for the nuclear statistical equilibrium distribution, and the progenitor model. in agreement with previous works, we show that the individual ec rates are the most important source of uncertainty in the simulations, while the other inputs only marginally influence the results. a recently proposed analytic formula to extrapolate microscopic results on stable nuclei for ec rates to the high densities and temperatures and the neutron-rich region, with a functional form motivated by nuclear-structure data and parameters fitted from large scale shell-model calculations, is shown to lead to a sizable (16%) reduction of the electron fraction at bounce compared to more primitive prescriptions for the rates, leading to smaller inner core masses and slower shock propagation. we show that the ec process involves ≈170 different nuclear species around 86kr, mainly in the n =50 shell closure region, and establish a list of the most important nuclei to be studied in order to constrain the global rates. | impact of electron capture rates for nuclei far from stability on core-collapse supernovae |
we construct isoentropic equations of state (eoss) of β -stable dense hadronic matter considering the possibility that a quark deconfinement phase transition can take place. these conditions can be actually realized in different astrophysical contexts like core-collapse supernovae (ccsne), during the early stages of the evolution of a newly formed neutron star (protoneutron star, pns) or in the postmerger compact object formed in binary neutron star (bns) mergers. we consider four different eoss to describe the hadronic phase: three eoss from relativistic mean field theory and one eos recently derived from microscopic calculations in the framework of the brueckner-hartree-fock approach. we combine these hadronic eoss with a quark matter eos obtained from a modified mit-bag model which takes into account some perturbative corrections in the grand canonical potential due to the quark-quark interaction. the two phases are then joined up through a gibbs construction. for each model we study thermal and neutrino trapping effects on the matter composition and consequently on the eos. we finally determine the pns static structure integrating the tolman-oppenheimer-volkoff equations. we find that the thermal contribution and particularly the effect of neutrino trapping play an important role on the full eos. the latter can get softer or stiffer according to the strangeness content in the hadronic phase. these effects are thus crucial to provide a proper description of the dynamical evolution of both the postmerger compact object formed in a bns merger or the pns formed in a ccsn. | isoentropic equations of state of β -stable hadronic matter with a quark phase transition |
super-kamiokande, a 50 ktons water cherenkov imaging detector situated 1000 meters underground in the kamioka mine, gifu, japan, has searched for neutrino signal correlated with sn2023ixf in a time window 2 days before the detection by oak st. observatory (2023-05-17 08:45:13 to 2023-05-19 08:45:13), during which super-kamiokande took data stably without dead time. | neutrino search for sn2023ixf in super-kamiokande |
we present an approximate treatment of the mixing between ντ (ν¯τ) and a sterile species νs (ν¯s) with a vacuum mass-squared difference of ∼102- 103 kev2 in protoneutron stars created in core-collapse supernovae. including production of sterile neutrinos through both resonant flavor conversion and collisions, we track the evolution of the ντ lepton number due to both escape of sterile neutrinos and diffusion. our approach provides a reasonable treatment of the pertinent processes discussed in previous studies and serves a pedagogical purpose to elucidate the relevant physics. we also discuss refinements needed to study more accurately how flavor mixing with sterile neutrinos affects protoneutron star evolution. | evolution of tau-neutrino lepton number in protoneutron stars due to active-sterile neutrino mixing |
we present neutrino capture cross sections on 13c at supernova neutrino energies, up to 50 mev. for both charged-current and neutral-current reactions partial cross sections are calculated using the statistical hauser-feschbach method. coherent elastic neutrino scattering cross section for a 13c target is also provided. | neutrino-13c cross sections at supernova neutrino energies |
the experimental detection of the ce$$\nu$$ ν ns allows the investigation of neutrinos and neutrino sources with all-flavor sensitivity. given its large content in neutrons and stability, pb is a very appealing choice as target element. the presence of the radioisotope $$^{210}$$ 210 pb (t$$_{1/2}\sim$$ 1 / 2 ∼ 22 yrs) makes natural pb unsuitable for low-background, low-energy event searches. this limitation can be overcome employing pb of archaeological origin, where several half-lives of $$^{210}$$ 210 pb have gone by. we present results of a cryogenic measurement of a 15 g pbwo$$_4$$ 4 crystal, grown with archaeological pb (older than $$\sim$$ ∼ 2000 yrs) that achieved a sub-kev nuclear recoil detection threshold. a ton-scale experiment employing such material, with a detection threshold for nuclear recoils of just 1 kev would probe the entire milky way for supernovae, with equal sensitivity for all neutrino flavors, allowing the study of the core of such exceptional events. | operation of an archaeological lead pbwo4 crystal to search for neutrinos from astrophysical sources with a transition edge sensor |
future large liquid-scintillator (ls) detectors are competitive with and complementary to the water-cherenkov detectors on the searches for diffuse supernova neutrino background and nucleon decay. in a companion paper, we have performed a systematic calculation of the neutral-current (nc) background induced by atmospheric neutrino interactions on 12c nuclei in ls detectors, which are expected to be crucially important for the experimental searches for the diffuse supernova neutrino background and nucleon decay. in this paper, we perform a systematic study on the measurement of the nc background and evaluate the associated uncertainties. we first exploit the characteristics of the nc background, in particular, the multiplicities of neutrons and pions, and the possible association with unstable residual nuclei. it turns out that the neutron multiplicity distribution is very powerful to discriminate among different models. then, we develop a maximum-likelihood method to allow an in situ measurement of the nc interactions with a triple-coincidence signature. finally, a data-driven approach is proposed to evaluate the uncertainty of the nc background in the search for the diffuse supernova neutrino background. we conclude that future large ls experiments like the jiangmen underground neutrino observatory will be able to make a unique contribution to the worldwide dataset to improve the prediction of atmospheric neutrino nc interactions on 12c. | neutral-current background induced by atmospheric neutrinos at large liquid-scintillator detectors. ii. methodology for in situ measurements |
spin of a test particle is a fundamental property that can affect its motion in a gravitational field. in this work we consider the effect of particle spin on its deflection angle and gravitational lensing in the equatorial plane of arbitrary stationary and axisymmetric spacetimes. to do this we developed a perturbative method that can be applied to spinning signals with arbitrary asymptotic velocity and takes into account the finite distance effect of the source and the observer. the deflection angle δφ and total travel time δt are expressed as (quasi-)power series whose coefficients are polynomials of the asymptotic expansion coefficients of the metric functions. it is found that when the spin and orbital angular momenta are parallel (or antiparallel), the deflection angle is decreased (or increased). apparent angles θ of the images in gravitational lensing and their time delays are also solved. in kerr spacetime, spin affects the apparent angle θk in a way similar to its effect on δφk . the time delay between signals with opposite spins is found to be proportional to the signal spin at leading order. these time delays might be used to constrain the spin to mass ratio of neutrinos. | effect of particle spin on trajectory deflection and gravitational lensing |
a protoneutron star (pns) is a newly formed compact object in a core collapse supernova. in this paper, the neutrino emission from the cooling process of a pns is investigated using two types of nuclear equation of state (eos). it is found that the neutrino signal is mainly determined by the high-density eos. the neutrino luminosity and mean energy are higher and the cooling time scale is longer for the softer eos. meanwhile, the neutrino mean energy and the cooling time scale are also affected by the low-density eos because of the difference in the population of heavy nuclei. heavy nuclei have a large scattering cross section with neutrinos owing to the coherent effects and act as thermal insulation near the surface of a pns. the neutrino mean energy is higher and the cooling time scale is longer for an eos with a large symmetry energy at low densities, namely a small density derivative coefficient of the symmetry energy, l . | heavy nuclei as thermal insulation for protoneutron stars |
the study of neutron rich matter, present in neutron star, proto-neutron stars and core-collapse supernovae, can lead to further understanding of the behavior of nuclear matter in highly asymmetric nuclei. heterogeneous structures are expected to exist in these systems, often referred to as nuclear pasta. we have carried out a systematic study of neutrino opacity for different thermodynamic conditions in order to assess the impact that the structure has on it. we studied the dynamics of the neutrino opacity of the heterogeneous matter at different thermodynamic conditions with semiclassical molecular dynamics model already used to study nuclear multifragmentation. for different densities, proton fractions and temperature, we calculate the very long range opacity and the cluster distribution. the neutrino opacity is of crucial importance for the evolution of the core-collapse supernovae and the neutrino scattering. | the neutrino opacity of neutron rich matter |
we exhibit a new instability that leads to "fast" coherent neutrino-antineutrino mixing in a dense neutrino cloud, arising from the standard four-fermi interaction induced by z exchange, and overlooked in the big existing literature on fast processes in this venue. it can play an essential role in creation of an abundance of pseudoscalar mesons of mass in the kev range in the early universe, at temperatures in the range 10-100 mev. also it can overpower existing calculations in the "neutrino bulb" regions of the supernova cloud. | neutrino-anti-neutrino instability in dense neutrino systems, with applications to the early universe and to supernovae |
the abundance of large clusters of nucleons in neutron-rich matter at subnuclear density is found to be greatly reduced by finite-temperature effects when matter is close to β equilibrium, compared to the case where the electron fraction is fixed at ye>0.1 , as often considered in the literature. large nuclei and exotic nonspherical nuclear configurations called pasta, favored in the vicinity of the transition to uniform matter at t =0 , dissolve at a relatively low temperature tu as protons leak out of nuclei and pasta. for matter at β equilibrium with a negligible neutrino chemical potential we find that tuβ≃4 ±1 mev for realistic equations of state. this is lower than the maximum temperature tmaxβ≃9 ±1 mev at which nuclei can coexist with a gas of nucleons and can be explained by a change in the nature of the transition to uniform matter called retrograde condensation. an important new finding is that coherent neutrino scattering from nuclei and pasta makes a modest contribution to the opacity under the conditions encountered in supernovas and neutron star mergers. this is because large nuclear clusters dissolve at most relevant temperatures, and at lower temperatures, when clusters are present, coulomb correlations between them suppress coherent neutrino scattering off individual clusters. implications for neutrino signals from galactic supernovas are briefly discussed. | nuclear pasta in hot dense matter and its implications for neutrino scattering |
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. | calibration of the advanced spectral leakage scheme for neutron star merger simulations, and extension to smoothed-particle hydrodynamics |
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 predictions of the effects of the neutrino-neutrino interaction. predictions for the production of sterile neutrinos, should they exist, will also be changed. | neutrino collective effects during their decoupling era in the early universe |
during a failed core-collapse supernova, the protoneutron star eventually collapses under its own gravitational field and forms a black hole. this collapse happens quickly, on the dynamical time of the protoneutron star, ≲0.5 ms. during this collapse, barring any excessive rotation, the entire protoneutron star is accreted into the newly formed black hole. the main source of neutrinos is now removed and the signal abruptly shuts off over this formation timescale. however, while the source of neutrinos is turned off, the arrival times at an earth-based detector will depend on the neutrino path. we show here that a modest amount of neutrinos, emitted just prior to the black hole forming, scatter on the infalling material into our line of sight and arrive after the formation of the black hole, up to 15 ms in our model. this neutrino echo, which we characterize with monte carlo simulations and analytic models, has a significantly higher average energy (upwards of ~50 mev) compared to the main neutrino signal, and for the canonical failed supernova explored here, is likely detectable in ${ \mathcal o }$ (10 kt) supernova neutrino detectors for galactic failed supernovae. the presence of this signal is important to consider if using black hole formation as a time post for triangulation or the post black hole timing profile for neutrino mass measurements. on its own, it can also be used to characterize or constrain the structure and nature of the accretion flow. | neutrino echos following black hole formation in core-collapse supernovae |
super-kamiokande has been searching for neutrino bursts characteristic of core-collapse supernovae continuously, in real time, since the start of operations in 1996. the present work focuses on detecting more distant supernovae whose event rate may be too small to trigger in real time, but may be identified using an offline approach. the analysis of data collected from 2008 to 2018 found no evidence of distant supernovae bursts. this establishes an upper limit of 0.29 yr-1 on the rate of core-collapse supernovae out to 100 kpc at 90% c.l. for supernovae that fail to explode and collapse directly to black holes the limit reaches to 300 kpc. | searching for supernova bursts in super-kamiokande iv |
we show that the backreaction of left-handed neutrinos out of equilibrium on the matter sector induces an electric current proportional to a magnetic field even without a chiral imbalance for electrons in core-collapse supernovae. we derive the transport coefficient of this effect based on the recently formulated chiral radiation transport theory for neutrinos. this chiral electric current generates a strong magnetic field via the so-called chiral plasma instability, which could provide a new mechanism for the strong and stable magnetic field of magnetars. we also numerically study the physical origin of the inverse cascade of the magnetic energy in the magnetohydrodynamics including this current. our results indicate that incorporating the chiral effects of neutrinos would drastically modify the hydrodynamic evolutions of supernovae, which may also be relevant to the explosion dynamics. | chiral plasma instability and inverse cascade from nonequilibrium left-handed neutrinos in core-collapse supernovae |
we study the neutrino pair annihilation into electron-positron pairs ( $\nu +\bar{\nu }\to {e}^{-}+{e}^{+}$ ) near the surface of a neutron star. the analysis is performed in the framework of extended theories of gravity. the latter induce a modification of the minimum photon sphere radius (rph) and the maximum energy deposition rate near rph, as compared to those of general relativity. these results might lead to an efficient mechanism for generating grbs. | effects of modified theories of gravity on neutrino pair annihilation energy deposition near neutron stars |
we develop a neutrino transfer code for core-collapse simulations that directly solves the multidimensional boltzmann equations in full general relativity. we employ the discrete ordinate method, which discretizes the 6d phase space. the code is an extension of our special relativistic code coupled to a newtonian hydrodynamics code, which is currently employed for core-collapse supernova simulations. in order to demonstrate our code's capability to treat general relativistic effects, we conduct some tests. we first compute the free streaming of neutrinos in the schwarzschild and kerr spacetimes and compare the results with the geodesic curves; in the schwarzschild case, we deploy not only a 1d grid in space under spherical symmetry but also a 2d spatial mesh under axisymmetry in order to assess the capability of the code to compute the spatial advection of neutrinos. second, we calculate the neutrino transport in a fixed matter background, which is taken from a core-collapse supernova simulation with our general relativistic but spherically symmetric boltzmann hydrodynamics code, to obtain a steady neutrino distribution; the results are compared with those given by the latter code. | multidimensional boltzmann neutrino transport code in full general relativity for core-collapse simulations |
core-collapse supernovae (ccsne) emit powerful gravitational waves (gws). since gws emitted by a source contain information about the source, observing gws from ccsne may allow us to learn more about ccsns. we study if it is possible to infer the iron core mass from the bounce and early ring-down gw signal. we generate gw signals for a range of stellar models using numerical simulations and apply machine learning to train and classify the signals. we consider an idealized favorable scenario. first, we use rapidly rotating models, which produce stronger gws than slowly rotating models. secondly, we limit ourselves to models with four different masses, which simplifies the selection process. we show that the classification accuracy does not exceed $\sim \! 70{{\ \mathrm{ per \, cent}}}$, signifying that even in this optimistic scenario, the information contained in the bounce, and early ring-down gw signal is not sufficient to precisely probe the iron core mass. this suggests that it may be necessary to incorporate additional information such as the gws from later post-bounce evolution and neutrino observations to accurately measure the iron core mass. | exploring supernova gravitational waves with machine learning |
the influence of thermal effects on neutrino-nucleus reactions occurring under supernova conditions is studied. the approach used is based on the quasiparticle random phase approximation extended to finite temperatures using the superoperator formalism. using the example of the 56fe and 82ge nuclei, a detailed analysis of the influence of thermal effects on the strength function of gamow-teller transitions, which dominate in the low-energy charge-neutral and charge-exchange reactions, is performed. neutrino cross sections for inelastic scattering and capture by hot nuclei are calculated and compared with the results of the shell model calculations. the influence of thermal effects on the spectrum of scattered neutrinos and on the process of energy exchange between neutrino radiation and nuclei is considered. the energy-loss rates in the process of neutrino-antineutrino pair emission by deexcitation of hot nuclei are calculated. | superoperator approach to the theory of hot nuclei and astrophysical applications. iii: neutrino-nucleus reactions in stars |
a new neutrino magnetohydrodynamics (nmhd) model is formulated, where the effects of the charged weak current on the electron-ion magnetohydrodynamic fluid are taken into account. the model incorporates in a systematic way the role of the fermi neutrino weak force in magnetized plasmas. a fast neutrino-driven short wavelengths instability associated with the magnetosonic wave is derived. such an instability should play a central role in strongly magnetized plasma as occurs in supernovae, where dense neutrino beams also exist. in addition, in the case of nonlinear or high frequency waves, the neutrino coupling is shown to be responsible for breaking the frozen-in magnetic field lines condition even in infinite conductivity plasmas. simplified and ideal nmhd assumptions were adopted and analyzed in detail. | neutrino magnetohydrodynamics |
we investigate a scalar field dark energy model (i.e., ϕcdm model) with massive neutrinos, where the scalar field possesses an inverse power-law potential, i.e., v (ϕ) ∝ϕ-α (α > 0). we find that the sum of neutrino masses σmν has significant impacts on the cmb temperature power spectrum and on the matter power spectrum. in addition, the parameter α also has slight impacts on the spectra. a joint sample, including cmb data from planck 2013 and wmap9, galaxy clustering data from wigglez and boss dr11, and jla compilation of type ia supernova observations, is adopted to confine the parameters. within the context of the ϕcdm model under consideration, the joint sample determines the cosmological parameters to high precision: the angular size of the sound horizon at recombination, the thomson scattering optical depth due to reionization, the physical densities of baryons and cold dark matter, and the scalar spectral index are estimated to be θ* = (1.0415-0.0011+0.0012) ×10-2, τ =0.0914-0.0242+0.0266, ωbh2 = 0.0222 ± 0.0005, ωch2 = 0.1177 ± 0.0036, and ns =0.9644-0.0119+0.0118, respectively, at 95% confidence level (cl). it turns out that α < 4.995 at 95% cl for the ϕcdm model. and yet, the λcdm scenario corresponding to α = 0 is not ruled out at 95% cl. moreover, we get σmν < 0.262 ev at 95% cl for the ϕcdm model, while the corresponding one for the λcdm model is σmν < 0.293 ev. the allowed scale of σmν in the ϕcdm model is a bit smaller than that in the λcdm model. it is consistent with the qualitative analysis, which reveals that the increases of α and σmν both can result in the suppression of the matter power spectrum. as a consequence, when α is larger, in order to avoid suppressing the matter power spectrum too much, the value of σmν should be smaller. | galaxy clustering, cmb and supernova data constraints on ϕcdm model with massive neutrinos |
preface; acknowledgements; acronyms and definitions; introduction; part i. theoretical foundations: 1. basic concepts; 2. kinetic equation; 3. averaging; 4. conservation laws and equilibrium; 5. relativistic bbgky hierarchy; 6. basic parameters in gases and plasmas; part ii. numerical methods: 7. the basics of computational physics; 8. direct integration of boltzmann equations; 9. multidimensional hydrodynamics; part iii. applications: 10. wave dispersion in relativistic plasma; 11. thermalization in relativistic plasma; 12. kinetics of particles in strong fields; 13. compton scattering in astrophysics and cosmology; 14. self-gravitating systems; 15. neutrinos, gravitational collapse and supernovae; appendices; bibliography; index. | relativistic kinetic theory |
the ev-scale sterile neutrino has been proposed to explain some anomalous results in experiments, such as the deficit of reactor neutrino fluxes and the excess of bar nuμ→bar nue in lsnd. this hypothesis can be tested by future core-collapse supernova neutrino detection independently since the active-sterile mixing scheme affects the flavor conversion of neutrinos inside the supernova. in this work, we compute the predicted supernova neutrino events in future detectors—dune, hyper-k, and juno—for neutrinos emitted during the neutronization burst phase when the luminosity of νe dominates the other flavors. we find that for a supernova occurring within 10 kpc, the difference in the event numbers with and without sterile neutrinos allows to exclude the sterile neutrino hypothesis at more than 99% confidence level robustly. the derived constraints on sterile neutrinos mixing parameters are comparably better than the results from cosmology and on-going or proposed reactor experiments by more than two orders of magnitude in the sin22θ14-δ m412 plane. | constraining sterile neutrinos by core-collapse supernovae with multiple detectors |
we revisit the rates of neutrino pair emission and absorption from nucleon-nucleon bremsstrahlung in supernova matter using the t-matrix formalism in the long-wavelength limit. based on two-body potentials of chiral effective field theory (χeft), we solve the lippmann-schwinger equation for the t-matrix including non-diagonal contributions. we consider final-state pauli blocking and hence our calculations are valid for nucleons with an arbitrary degree of degeneracy. we also explore the in-medium effects on the t-matrix and find that they are relatively small for supernova matter. we compare our results with one-pion exchange rates, commonly used in supernova simulations, and calculations using an effective on-shell diagonal t-matrix from measured phase shifts. we estimate that multiple-scattering effects and correlations due to the random phase approximation introduce small corrections on top of the t-matrix results at subsaturation densities. a numerical table of the structure function is provided that can be used in supernova simulations. | chiral effective field theory description of neutrino nucleon-nucleon bremsstrahlung in supernova matter |
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