Core-collapse Supernovae Research Articles

The Jets and the Neutron Star Kick Velocity of the Supernova Remnant CTB 1

We identify jet-shaped morphology in the core-collapse supernova remnant (SNR) CTB 1 that includes two opposite structural features. We identify these as the imprints of a pair of jets that were among the last jets to explode the massive stellar progenitor of CTB 1. We find the projected angle between the jets’ axis and the direction of the pulsar velocity, which is the neutron star natal kick, to be α = 78°. We tentatively identify possible signatures of a second pair of opposite jets along a different direction. If this identification holds, SNR CTB 1 has a point-symmetric structure. The morphology and large angle of the jets’ axis to kick velocity are expected in the jittering jets explosion mechanism of core-collapse supernovae.

Big-bang Nucleosynthesis on a bubble universe nucleated in Kerr-AdS5.

Modelling the Galactic chemical evolution (GCE) of short-lived radioisotopes (SLRs, with half-lives of the order of million years) can provide timing information on recent nucleosynthesis. The knowledge of their spatial distribution throughout the interstellar medium (ISM) is crucial. We are using a three-dimensional GCE model to investigate the evolution of four SLRs: \(^{53}\)Mn from supernovae of type Ia (SNeIa), \(^{60}\)Fe from core-collapse supernovae (CCSNe), \(^{182}\)Hf from stellar winds from intermediate mass stars (IMSs), and \(^{244}\)Pu from neutron star mergers (NSMs) to explain the recent (within the last $\approx 1 -- 20$ Myr) deposition of live SLRs into deep-sea reservoirs. We find that although these SLRs are produced at very different nucleosynthetic sites, they are deposited on Earth conjointly.

Nonlinear Evolution of Fast Collective Neutrino Oscillations in Core-collapse Supernovae

According to one of the most promising supernova theories, the neutrino-heating mechanism, neutrinos are responsible for transferring the energy released during the gravitational collapse of massive stars to their surroundings. If neutrino flavors are converted fast in the cores, the efficiency of neutrino heating is enhanced and can change the dynamics of the shock wave in supernovae. In this article, we investigate the dynamics of fast neutrino flavor conversions with collisions under energy-dependent treatment in detail. For the first time, we use a realistic initial condition, which is taken from the results of the self-consistent, realistic Boltzmann simulations in two spatial dimensions under axisymmetry. We report that the neutrino flavor conversion will be significantly enhanced if the energy-dependent collision term is considered in the neutrino transport equation which has been ignored in previous studies. We present the preliminary results of our investigation here, which are consistent with other studies which were conducted under simple treatments. It is believed that such findings may have an impact on the explosion mechanism of core-collapse supernovae, \mbox{nucleosynthesis and neutrino astronomy.

Ab-initio General-relativistic Neutrino-radiation Hydrodynamics Simulations of Long-lived Neutron Star Merger Remnants to Neutrino Cooling Timescales

We perform the first 3D ab-initio general-relativistic neutrino-radiation hydrodynamics of a long-lived neutron star merger remnant spanning a fraction of its cooling timescale. We find that neutrino cooling becomes the dominant energy loss mechanism after the gravitational-wave dominated phase (∼20 ms postmerger). Electron flavor antineutrino luminosity dominates over electron flavor neutrino luminosity at early times, resulting in a secular increase of the electron fraction in the outer layers of the remnant. However, the two luminosities become comparable ∼20–40 ms postmerger. A dense gas of electron antineutrinos is formed in the outer core of the remnant at densities ∼1014.5 g cm−3, corresponding to temperature hot spots. The neutrinos account for ∼10% of the lepton number in this region. Despite the negative radial temperature gradient, the radial entropy gradient remains positive, and the remnant is stably stratified according to the Ledoux criterion for convection. A massive accretion disk is formed from the material squeezed out of the collisional interface between the stars. The disk carries a large fraction of the angular momentum of the system, allowing the remnant massive neutron star to settle to a quasi-steady equilibrium within the region of possible, stable, rigidly rotating configurations. The remnant is differentially rotating, but it is stable against the magnetorotational instability. Other MHD mechanisms operating on longer timescales are likely responsible for the removal of the differential rotation. Our results indicate the remnant massive neutron star is thus qualitatively different from a protoneutron stars formed in core-collapse supernovae.

Long-rising Type II Supernovae in the Zwicky Transient Facility Census of the Local Universe

SN 1987A was an unusual hydrogen-rich core-collapse supernova originating from a blue supergiant star. Similar blue supergiant explosions remain a small family of events, and are broadly characterized by their long rises to peak. The Zwicky Transient Facility Census of the Local Universe (CLU) experiment aims to construct a spectroscopically complete sample of transients occurring in galaxies from the CLU galaxy catalog. We identify 13 long-rising (>40 days) Type II supernovae from the volume-limited CLU experiment during a 3.5 yr period from 2018 June to 2021 December, approximately doubling the previously known number of these events. We present photometric and spectroscopic data of these 13 events, finding peak r-band absolute magnitudes ranging from −15.6 to −17.5 mag and the tentative detection of Ba ii lines in nine events. Using our CLU sample of events, we derive a long-rising Type II supernova rate of Mpc−3 yr−1, ≈1.4% of the total core-collapse supernova rate. This is the first volumetric rate of these events estimated from a large, systematic, volume-limited experiment.

Characterizing the Directionality of Gravitational Wave Emission from Matter Motions within Core-collapse Supernovae

We analyze the directional dependence of the gravitational wave (GW) emission from 15 3D neutrino radiation hydrodynamic simulations of core-collapse supernovae (CCSNe). Using spin weighted spherical harmonics, we develop a new analytic technique to quantify the evolution of the distribution of GW emission over all angles. We construct a physics-informed toy model that can be used to approximate GW distributions for general ellipsoid-like systems, and use it to provide closed form expressions for the distribution of GWs for different CCSN phases. Using these toy models, we approximate the protoneutron star (PNS) dynamics during multiple CCSN stages and obtain similar GW distributions to simulation outputs. When considering all viewing angles, we apply this new technique to quantify the evolution of preferred directions of GW emission. For nonrotating cases, this dominant viewing angle drifts isotropically throughout the supernova, set by the dynamical timescale of the PNS. For rotating cases, during core bounce and the following tens of milliseconds, the strongest GW signal is observed along the equator. During the accretion phase, comparable—if not stronger—GW amplitudes are generated along the axis of rotation, which can be enhanced by the low T/∣W∣ instability. We show two dominant factors influencing the directionality of GW emission are the degree of initial rotation and explosion morphology. Lastly, looking forward, we note the sensitive interplay between GW detector site and supernova orientation, along with its effect on detecting individual polarization modes.

Spin-flavor precession of Dirac neutrinos in dense matter and its potential in core-collapse supernovae

Spin-flavor precession of Dirac neutrinos in dense matter and its potential in core-collapse supernovae

Probing the Low-mass End of Core-collapse Supernovae Using a Sample of Strongly-stripped Calcium-rich Type IIb Supernovae from the Zwicky Transient Facility

The fate of stars in the zero-age main-sequence (ZAMS) range ≈8–12 M ⊙ is unclear. They could evolve to form white dwarfs or explode as electron-capture supernovae (SNe) or iron core-collapse SNe (CCSNe). Even though the initial mass function indicates that this mass range should account for over 40% of all CCSN progenitors, few have been observationally confirmed, likely due to the faintness and rapid evolution of some of these transients. In this paper, we present a sample of nine Ca-rich/O-poor Type IIb SNe detected by the Zwicky Transient Facility with progenitors likely in this mass range. These sources have a [Ca ii] λ λ7291, 7324/[O i] λ λ6300, 6364 flux ratio of ≳2 in their nebular spectra. Comparing the measured [O i] luminosity (≲1039 erg s−1) and derived oxygen mass (≈0.01 M ⊙) with theoretical models, we infer that the progenitor ZAMS mass for these explosions is less than 12 M ⊙. The ejecta properties (M ej ≲ 1 M ⊙ and E kin ∼ 1050 erg) are also consistent. The low ejecta mass of these sources indicates a class of strongly-stripped SNe that is a transition between the regular stripped-envelope SNe and ultra-stripped SNe. The progenitor could be stripped by a main-sequence companion and result in the formation of a neutron star−main sequence binary. Such binaries have been suggested to be progenitors of neutron star−white dwarf systems that could merge within a Hubble time and be detectable with LISA.

Neutron Star Kicks and Implications for Their Rotation at Birth

Neutron stars are born out of core-collapse supernovae, and they are imparted natal kicks at birth as a consequence of asymmetric ejection of matter and possibly neutrinos. Unless the force resulting from the kicks is exerted exactly at their center, it will also cause the neutron star to rotate. In this paper, we discuss the possibility that neutron stars may receive off-center natal kicks at birth, which imprint a natal rotation. In this scenario, the observed pulsar spin and transverse velocity in the Galaxy are expected to correlate. We develop a model of the natal rotation imparted to neutron stars and constrain it by the observed population of pulsars in our Galaxy. When considering a single-kick position parameter, we find that the location of the off-center kick is km at 90% confidence, and is robust when considering pulsars with different observed periods, transverse velocities, and ages. Nonetheless, the model encounters challenges in effectively fitting the data, particularly at small transverse velocities, prompting the exploration of alternative models that include more complex physics. Our framework could be used as a guide for core-collapse simulations of massive stars.

On the core-collapse supernova explanation for LAMOST J1010 + 2358

ABSTRACT Low-metallicity very massive stars with an initial mass of ∼140–$260\, \mathrm{M}_\odot$ are expected to end their lives as pair-instability supernovae (PISNe). The abundance pattern resulting from a PISN differs drastically from regular core-collapse supernova (CCSN) models and is expected to be seen in very metal-poor (VMP) stars of [Fe/H] ≲ −2. Despite the routine discovery of many VMP stars, the unique abundance pattern expected from PISNe has not been unambiguously detected. The recently discovered VMP star LAMOST J1010 + 2358, however, shows a peculiar abundance pattern that is remarkably well fit by a PISN, indicating the potential first discovery of a bonafide star born from gas polluted by a PISN. In this paper, we study the detailed nucleosynthesis in a large set of models of CCSN of Pop III and Pop II star of metallicity [Fe/H] = −3 with masses ranging from 12 to $30\, \mathrm{M}_\odot$. We find that the observed abundance pattern in LAMOST J1010 + 2358 can be fit at least equally well by CCSN models of ∼12–$14\, \mathrm{M}_\odot$ that undergo negligible fallback following the explosion. The best-fitting CCSN models provide a fit that is even marginally better than the best-fitting PISN model. We conclude the measured abundance pattern in LAMOST J1010 + 2358 could have originated from a CCSN and therefore cannot be unambiguously identified with a PISN given the set of elements measured in it to date. We identify key elements that need to be measured in future detections in stars like LAMOST J1010 + 2358 that can differentiate between CCSN and PISN origin.

Neutrino-driven massive stellar explosions in 3D fostered by magnetic fields via turbulent α-effect

ABSTRACT We investigate the influence of magnetic field amplification on the core-collapse supernovae in highly magnetized progenitors through 3D simulations. By considering rotating models, we observe a strong correlation between the exponential growth of the magnetic field in the gain region and the initiation of shock revival, with a faster onset compared to the non-rotating model. We highlight that the mean magnetic field experiences exponential amplification as a result of α-effect in the dynamo process, which works efficiently with the increasing kinetic helicity of the turbulence within the gain region. Our findings indicate that the significant amplification of the mean magnetic fields leads to the development of locally intense turbulent magnetic fields, particularly in the vicinity of the poles, thereby promoting the revival of the shock by neutrino heating.

Bayesian model selection for GRB 211211A through multiwavelength analyses

ABSTRACT Although GRB 211211A is one of the closest gamma-ray bursts (GRBs), its classification is challenging because of its partially inconclusive electromagnetic signatures. In this paper, we investigate four astrophysical scenarios as possible progenitors for GRB 211211A: a binary neutron star merger, a black hole–neutron star merger, a core-collapse supernova, and an r-process enriched core collapse of a rapidly rotating massive star (a collapsar). We perform a large set of Bayesian multiwavelength analyses based on different models describing these scenarios and priors to investigate which astrophysical scenarios and processes might be related to GRB 211211A. Our analysis supports previous studies in which the presence of an additional component, likely related to r-process nucleosynthesis, is required to explain the observed light curves of GRB 211211A, as it cannot be explained solely as a GRB afterglow. Fixing the distance to about $350~\rm Mpc$, namely the distance of the possible host galaxy SDSS J140910.47+275320.8, we find a statistical preference for a binary neutron star merger scenario.

Chemodynamical study of two CEMP-no stars from the Hamburg/ESO Survey

ABSTRACT The Carbon-Enhanced Metal-Poor (CEMP) stars with no enhancement of neutron-capture elements, the so-called CEMP-no stars are believed to be the direct descendants of first-generation stars and provide a unique opportunity to probe the early Galactic nucleosynthesis. We present a detailed chemical and kinematic analysis for two extremely metal-poor stars HE 1243 − 2408 and HE 0038 − 0345 using high-resolution (R∼86 000) HERMES spectra. For the object HE 1243 − 2408, we could make a detailed comparison with the available literature values; however, only limited information is available for the other object HE 0038 − 0345. Our estimated metallicity for these two objects are −3.05 and −2.92, respectively. With estimated [C/Fe] (1.03 and 1.05) and [Ba/Fe] (−0.18 and −0.11), respectively, the objects are found to be bonafide CEMP-no stars. From the observed abundances of C, Na, Mg, and Ba (i.e. A(C), A(Na), A(Mg), A(Ba)), the objects are found to belong to Group II CEMP-no stars. A detailed abundance profile analysis indicates that the objects are accreted from dSph satellite galaxies that support hierarchical galaxy assembly. Further, our analysis shows that the progenitors of the stars are likely Pop II Core-Collapse Supernovae. The object HE 0038 − 0345 is found to be a high-energy, prograde, outer-halo object, and HE 1243 − 2408 is found to be a high-energy, retrograde, inner-halo object. Our detailed chemodynamical analysis shows that HE 1243 − 2408 is related to I’itoi structure, where as HE 0038 − 0345 is likely related to Sgr or GSE events. The mass of the progenitor galaxies of the programme stars inferred from their dynamics is at par with their likely origin in massive dSph galaxies.

Core-collapse supernova inside the core of a young massive star cluster: 3D MHD simulations

ABSTRACT Young massive stars in compact stellar clusters could end their evolution as core-collapse supernovae a few million years after the cluster was built. The blast wave of a supernova propagates through the inner cluster region with multiple stellar winds of young luminous stars. We present the results of 3D magnetohydrodynamic simulations of the plasma flows produced by a supernova event inside a cluster with a population of massive stars similar to that in Westerlund 1. We followed its evolution over a few thousand years (i.e. a few shock crossing times). The plasma temperature, density, and magnetic field, which are highly disturbed by supernova event, relax to values close to the initial over the studied period. The relaxation time of a cluster is a few thousand years, which is a sizeable fraction of the period between the successive supernova events for a massive cluster of a few million years age. The spectra of the cluster diffuse X-ray emission simulated here should be representative for the galactic and extragalactic young massive clusters. The resultant magnetic fields are highly intermittent, so we derived the volume filling factors for a set of magnetic field ranges. Highly amplified magnetic fields of magnitude well above 100 µG fill in a few per cent of the cluster volume, but still dominate the magnetic energy. The structure of the magnetic fields and high-velocity plasma flows with shocks in the system are favourable for both proton and electron acceleration to energies well above TeV.

Influence of the tetraneutron on the EoS under core-collapse supernova and heavy-ion collision conditions

Context. Recently, a resonant state of four neutrons (tetraneutron) with an energy of E4n = 2.37 ± 0.38(stat) ± 0.44(sys) MeV and a width of Γ = 1.75 ± 0.22(stat) ± 0.30(sys) MeV was reported. Aims. In this work, we analyze the effect of including such an exotic state on the yields of other light clusters; these clusters not only form in astrophysical sites, such as core-collapse supernovae and neutron star (NS) mergers, but also in heavy-ion collisions. Methods. To this aim, we used a relativistic mean-field (RMF) formalism, where we consider in-medium effects in a two-fold way – that is, via the couplings of the clusters to the mesons, and via a binding energy shift – to compute the low-density equation of state (EoS) for nuclear matter at finite temperature and fixed proton fraction. We consider five light clusters – namely deuterons, tritons, helions, α-particles, and 6He – immersed in a gas of protons and neutrons, and we calculate their abundances and chemical equilibrium constants with and without the tetraneutron. We also analyze how the associated energy of the tetraneutron would influence such results. Results. We find that the low-temperature, neutron-rich systems are the ones most affected by the presence of the tetraneutron, making NSs excellent environments for their formation. Moreover, its presence in strongly asymmetric matter may increase the proton and α-particle fractions considerably. This may have an influence on the dissolution of the accretion disk of the merger of two NSs.

Exploring Neutrino Mass Orderings through Supernova Neutrino Detection

Core-collapse supernovae (SNe) are one of the most powerful cosmic sources of neutrinos, with energies of several MeV. The emission of neutrinos and antineutrinos of all flavors carries away the gravitational binding energy of the compact remnant and drives its evolution from the hot initial to the cold final states. Detecting these neutrinos from Earth and analyzing the emitted signals present a unique opportunity to explore the neutrino mass ordering problem. This research outlines the detection of neutrinos from SNe and their relevance in understanding the neutrino mass ordering. The focus is on developing a model-independent analysis strategy, achieved by comparing distinct detection channels in large underground detectors. The objective is to identify potential indicators of mass ordering within the neutrino sector. Additionally, a thorough statistical analysis is performed on the anticipated neutrino signals for both mass orderings. Despite uncertainties in supernova explosion parameters, an exploration of the parameter space reveals an extensive array of models with significant sensitivity to differentiate between mass orderings. The assessment of various observables and their combinations underscores the potential of forthcoming supernova observations in addressing the neutrino mass ordering problem.

Synthetic light curves and spectra from a self-consistent 2D simulation of an ultra-strippped supernova

ABSTRACT Spectroscopy is an important tool for providing insights into the structure of core-collapse supernova explosions. We use the Monte Carlo radiative transfer code artis to compute synthetic spectra and light curves based on a two-dimensional explosion model of an ultra-stripped supernova. These calculations are designed both to identify observable fingerprints of ultra-stripped supernovae and as a proof of principle for using synthetic spectroscopy to constrain the nature of stripped-envelope supernovae more broadly. We predict characteristic spectral and photometric features for our ultra-stripped explosion model, and find that these do not match observed ultra-stripped supernova candidates like SN 2005ek. With a peak bolometric luminosity of $6.8\times 10^{41}\, \mathrm{erg}\, \mathrm{s}^{-1}$, a peak magnitude of $-15.9\, \mathrm{mag}$ in R band, and Δm15,R = 3.50, the model is even fainter and evolves even faster than SN 2005ek as the closest possible analogue in photometric properties. The predicted spectra are extremely unusual. The most prominent features are Mg ii lines at $2 {,}800\, {\mathring{\rm A}}$ and $4 {,}500\, {\mathring{\rm A}}$ and the infrared Ca triplet at late times. The Mg lines are sensitive to the multidimensional structure of the model and are viewing-angle dependent. They disappear due to line blanketing by iron group elements in a spherically averaged model with additional microscopic mixing. In future studies, multi-D radiative transfer calculations need to be applied to a broader range of models to elucidate the nature of observed Type Ib/c supernovae.

Predicting Gravitational Waves from Jittering-jets-driven Core Collapse Supernovae

I estimate the frequencies of gravitational waves from jittering jets that explode core collapse supernovae (CCSNe) to crudely be 5–30 Hz, and with strains that might allow detection of Galactic CCSNe. The jittering jets explosion mechanism (JJEM) asserts that most CCSNe are exploded by jittering jets that the newly born neutron star (NS) launches within a few seconds. According to the JJEM, instabilities in the accreted gas lead to the formation of intermittent accretion disks that launch the jittering jets. Earlier studies that did not include jets calculated the gravitational frequencies that instabilities around the NS emit to have a peak in the crude frequency range of 100–2000 Hz. Based on a recent study, I take the source of the gravitational waves of jittering jets to be the turbulent bubbles (cocoons) that the jets inflate as they interact with the outer layers of the core of the star at thousands of kilometers from the NS. The lower frequencies and larger strains than those of gravitational waves from instabilities in CCSNe allow future, and maybe present, detectors to identify the gravitational wave signals of jittering jets. Detection of gravitational waves from local CCSNe might distinguish between the neutrino-driven explosion mechanism and the JJEM.

An aspherical distribution for the explosive burning ash of core-collapse supernovae

An aspherical distribution for the explosive burning ash of core-collapse supernovae

Neutrino signatures of 100 2D Axisymmetric Core-Collapse Supernova Simulations

ABSTRACT We present in this paper a public data release of an unprecedentedly large set of core-collapse supernova (CCSN) neutrino emission models, comprising 100 detailed 2D axisymmetric radiation-hydrodynamic simulations evolved out to as late as ∼5 s post-bounce and spanning an extensive range of massive-star progenitors. The motivation for this paper is to provide a physically and numerically uniform benchmark data set to the broader neutrino detection community to help it characterize and optimize subsurface facilities for what is likely to be a once-in-a-lifetime galactic supernova burst event. With this release, we hope to (1) help the international experiment and modelling communities more efficiently optimize the retrieval of physical information about the next galactic CCSN, (2) facilitate the better understanding of core-collapse theory and modelling among interested experimentalists, and (3) help further integrate the broader supernova neutrino community.