Stars of ~8-100 solar masses end their lives as core-collapse supernovae (SNe). In the process they emit a powerful burst of neutrinos, produce a variety of elements, and leave behind either a neutron star or a black hole. The wide mass range for SN progenitors results in diverse neutrino signals, explosion energies, and nucleosynthesis products. A major mechanism to produce nuclei heavier than iron is rapid neutron capture, or the r process. This process may be connected to SNe in several ways. A brief review is presented on current understanding of neutrino emission, explosion, and nucleosynthesis of SNe.
Hypothetical particles called heavy neutral leptons (HNLs) can be produced in large quantities in the cores of supernovae during the first seconds of the explosion. These particles then decay, producing secondary energetic neutrinos that can be detected by neutrino detectors. In this paper, I identify a region of the HNL parameter space that could be tested using this method, assuming a supernova explosion at distances from 0.2 to 10 kpc. The range of HNLs masses $m_N \sim 160-700$ MeV and lifetimes of $τ_N \gtrsim 0.02$ seconds can be probed using the Hyper-Kamiokande neutrino detector. This …
Axion-like particles (ALPs) are a class of hypothetical pseudoscalar particles which feebly interact with ordinary matter. The hot plasma of core-collapse supernovae is a possible laboratory to explore physics beyond the standard model including ALPs. Once produced, some of the ALPs can be absorbed by the supernova matter and affect energy transfer. In this study, we calculate the ALP emission in core-collapse supernovae and the backreaction on supernova dynamics consistently. It is found that the stalled bounce shock can be revived if the coupling between ALPs and photons is as high as g_{ag}…
Heavy axion-like particles (ALPs), with masses $m_a \gtrsim 100$ keV, coupled with photons, would be copiously produced in a supernova (SN) core via Primakoff process and photon coalescence. Using a state-of-the-art SN model, we revisit the energy-loss SN 1987A bounds on axion-photon coupling. Moreover, we point out that heavy ALPs with masses $m_a \gtrsim 100$ MeV and axion-photon coupling $g_{aγ} \gtrsim 4 \times 10^{-9}$ GeV$^{-1}$ would decay into photons behind the shock-wave producing a possible enhancement in the energy deposition that would boost the SN shock revival.
We derive new constraints on the coupling of heavy pseudoscalar (axion-like) particles to photons, based on the gamma ray flux expected from the decay of these particles into photons. After being produced in the supernova core, these heavy axion-like particles would escape and a fraction of them would decay into photons before reaching the Earth. We have calculated the expected flux on Earth of these photons from the supernovae SN 1987A and Cassiopeia A and compared our results to data from the Fermi Large Area Telescope. This analysis provides strong constraints on the parameter space for axi…
Heavy sterile neutrinos with masses ${\mathcal O}(100)$ 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 $\sin^2 θ\lesssim 5 \times 10^{-7}$. 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 …
Axion-like particles (ALPs) are hypothetical bosons which may couple with photons. Since many ALPs can be emitted from hot and dense astrophysical plasma, nearby supernovae (SNe) are a possible probe into their properties including the ALP mass m_a and the coupling constant g_{ag} between ALPs and photons. I calculated ALP emission from a type Ia SN (SN Ia) model with the near-Chandrasekhar mass. It is found that the ALP luminosity from SNe Ia reaches ~10^43(g_{ag}/10^-10 GeV^-1)^2 erg s^-1 if m_a < 1 MeV. Heavy ALPs emitted from SNe are unstable and decay into photons. I predict the time dela…
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 non-interacting particles, for the description of light and heavy clusters becomes invalid for warm nuclear matter near the saturation density. This has important c…
Heavy nuclei such as nickel-56 are synthesized in a wide range of core-collapse supernovae (CCSN), including energetic supernovae associated with gamma-ray bursts (GRBs). Recent studies suggest that jet-like outflows are a common feature of CCSN. These outflows may entrain synthesized nuclei at launch or during propagation, and provide interesting multi-messenger signals including heavy ultra-high energy cosmic rays. Here, we investigate the destruction processes of nuclei during crossing from the stellar material into the jet material via a cocoon, and during propagation after being successfu…
Herein, we review the nuclear equations of state (EOSs) %for core-collapse supernova simulations and the constituent nuclei of core-collapse supernovae (CCSNe) and their roles in CCSN simulations. Various nuclei such as deuterons, iron, and extremely neutron-rich nuclei compose in the central engines of CCSNe. The center of a collapsing core is dominated by neutron-rich heavy nuclei prior to the occurrence of core bounce. Their weak interactions significantly affect the neutrino emission and the size of the produced proto-neutron star. After a core bounce, heavy nuclei are dissolved to protons…
We propose a $(p,xn)$ mechanism with dynamic production as a new set of nuclear reactions that could produce high density neutrons and explain the r- and rp-elements. We calculate the rate of thorium and uranium produced by our proposed mechanism and show that it is compatible with different stellar conditions found in explosive events at an initial temperature of $T \geq 3\times 10^{9} K$ with a "freeze-out" by a neutrino-driven wind. We show that charged particle reactions could explain the discrepancies in the abundances of ${}^{232}Th$ and ${}^{235,238}U$ nucleochronometers. We extend the …
The observational signatures of the first cosmic explosions and their chemical imprint on second-generation stars both crucially depend on how heavy elements mix within the star at the earliest stages of the blast. We present numerical simulations of the early evolution of Population III pair-instability supernovae with the new adaptive mesh refinement code CASTRO. In stark contrast to 15 - 40 Msun core-collapse primordial supernovae, we find no mixing in most 150 - 250 Msun pair-instability supernovae out to times well after breakout from the surface of the star. This may be the key to determ…
Core-collapse supernovae (CCSNe) are the extremely energetic deaths of massive stars. They play a vital role in the synthesis and dissemination of many heavy elements in the universe. In the past, CCSN nucleosynthesis calculations have relied on artificial explosion methods that do not adequately capture the physics of the innermost layers of the star. The PUSH method, calibrated against SN1987A, utilizes the energy of heavy-flavor neutrinos emitted by the proto-neutron star (PNS) to trigger parametrized explosions. This makes it possible to follow the consistent evolution of the PNS and to en…
Magnetorotational supernovae are a rare type of core-collapse supernovae where the magnetic field and rotation play a central role in the dynamics of the explosion. We present the post-processed nucleosynthesis of state-of-the-art neutrino-MHD supernova models that follow the post explosion evolution for few seconds. We find three different dynamical mechanisms to produce heavy r-process elements: i) a prompt ejection of matter right after core bounce, ii) neutron-rich matter that is ejected at late times due to a reconfiguration of the protoneutronstar shape, iii) small amount of mass ejected…
The conventional neutrino transport theory for core-collapse supernovae misses one key property of neutrinos: the left-handedness. The chirality of neutrinos modifies the hydrodynamic behavior at the macroscopic scale and leads to topological transport phenomena. We argue that such transport phenomena should play important roles in the evolution of core-collapse supernovae, and, in particular, lead to a tendency toward the inverse energy cascade from small to larger scales, which may be relevant to the origin of the supernova explosion.
Intensity interferometry is a technique that has been used to measure the size of sources ranging from the quark-gluon plasma formed in heavy ion collisions to the radii of stars. We investigate using the same technique to measure proto-neutron star (PNS) radii with the neutrino signal received from a core-collapse supernovae. Using a full wave-packet analysis, including the neutrino mass for the first time, we derive criteria where the effect can be expected to provide the desired signal, and find that neutrinos from the next Galactic supernova should contain extractable PNS radius informatio…
Super-knee cosmic rays from interacting supernovae
Frontier Research Institute for Interdisciplinary Sciences, Tohoku University（东北大学前沿跨学科研究院）；Astronomical Institute, Graduate School of Science, Tohoku University（东北大学理学研究科天文研究所）
We propose that nebular H-alpha emission as detected in the Type Ic superluminous supernova iPTF13ehe stems from matter which is stripped from a companion star when the supernova ejecta collide with it. The temporal evolution, the line broadening, and the overall blueshift of the emission are consistent with this interpretation. We scale the nebular H-alpha luminosity predicted for Type Ia supernovae in single-degenerate systems to derive the stripped mass required to explain the H-alpha luminosity of iPTF13ehe. We find a stripped mass of 0.1 - 0.9 solar masses, assuming that the supernova lum…
We use non-local thermal equilibrium radiative transport modeling to examine observational signatures of sub-Chandrasekhar mass double detonation explosions in the nebular phase. Results range from spectra that look like typical and subluminous Type Ia supernovae (SNe) for higher mass progenitors to spectra that look like Ca-rich transients for lower mass progenitors. This ignition mechanism produces an inherent relationship between emission features and the progenitor mass as the ratio of the nebular [Ca II]/[Fe III] emission lines increases with decreasing white dwarf mass. Examining the [Ca…
We introduce a family of equations of state (EoS) for hybrid neutron star (NS) matter that is obtained by a two-zone parabolic interpolation between a soft hadronic EoS at low densities and a stiff quark matter EoS with color superconductivity at high densities within a finite region of baryonic chemical potentials $μ_B^h < μ_B < μ_B^q$. We consider two scenarios corresponding to a cross-over and a strong first-order transition between quark and hadron phases considered at finite and zero temperatures. This allows us to analyze the effects of finite entropy on the EoS and mass-radius relation …
We perform hydrodynamical calculations of core-collapse supernovae (SNe) with low explosion energies. These SNe do not have enough energy to eject the whole progenitor and most of the progenitor falls back to the central remnant. We show that such fallback SNe can have a variety of light curves (LCs) but their photospheric velocities can only have some limited values with lower limits. We also perform calculations of nucleosynthesis and LCs of several fallback SN model, and find that a fallback SN from the progenitor with a main-sequence mass of 13 Msun can account for the properties of the pe…
The origin of the diverse light-curve shapes of Type II supernovae (SNe), and whether they come from similar or distinct progenitors, has been actively discussed for decades. Here we report spectropolarimetry of two fast declining Type II (Type IIL) SNe: SN 2013ej and SN 2017ahn. SN 2013ej exhibited high continuum polarization from very soon after the explosion to the radioactive tail phase with time-variable polarization angles. The origin of this polarimetric behavior can be interpreted as the combination of two different aspherical structures, namely an aspherical interaction of the SN ejec…
Understanding how massive stars die as supernovae is a crucial question in modern astrophysics. Supernovae are powerful stellar explosions and key drivers in the cosmic baryonic cycles by injecting their explosion energy and heavy elements to the interstellar medium that forms new stars. After decades of effort, astrophysicists have built up a stand model for the explosion mechanism of massive stars. However, this model is challenged by new kinds of stellar explosions discovered in the recent transit surveys. In particular, the new population called superluminous supernovae, which are a hundre…
The work reported in this dissertation will concern the study of kinetics, cycles and quantum mechanic processes of nuclear reactions involved in massive stars together with explosive nucleosynthesis phenomena having a key role in supernovae explosion. Four main fields will be explored: physics of nuclear reaction, hydrogen burning, CNO cycles and explosive supernovae phenomena. The first chapter will provide an overview of the background of the nuclear physics and of the potential approaches to the field as quantum mechanic aspects, cross section and Maxwell-Boltzmann distribution. The next c…
We study the effect of a dibaryon, S, in the mass range 1860 MeV < m_S < 2054 MeV, which is heavy enough not to disturb the stability of nuclei and light enough to possibly be cosmologically metastable. Such a deeply bound state can act as a baryon sink in regions of high baryon density and temperature. We find that the ambient conditions encountered inside a newly born neutron star are likely to sustain a sufficient population of hyperons to ensure that a population of S dibaryons can equilibrate in less than a few seconds. This would be catastrophic for the stability of neutron stars and the…
We investigate whether the recent ultra-high energy (UHE) neutrino events detected at the IceCube neutrino observatory could come from the decay of charmed mesons produced within the mildly relativistic jets of supernova-like astrophysical sources. We demonstrate that the $5.7σ$ excess of neutrinos observed by IceCube in the energy range 30 TeV--2 PeV can be explained by a diffuse flux of neutrinos produced in such slow-jet supernovae, using the values of astrophysical and QCD parameters within the theoretical uncertainties associated with neutrino production from charmed meson decay in astrop…
Inhomogeneities in a synchrotron source can severely affect the conclusions drawn from observations regarding the source properties. However, their presence is not always easy to establish, since several other effects can give rise to similar observed characteristics. It is argued that the recently observed broadening of the radio spectra and/or light curves in some of the type Ib/c supernovae is a direct indication of inhomogeneities. As compared to a homogeneous source, this increases the deduced velocity of the forward shock and the observed correlation between total energy and shock veloci…
We investigate the low-luminosity supernova SN 2016bkv and its peculiar early-time interaction. For that, we compute radiative transfer models using the CMFGEN code. Because SN 2016bkv shows signs of interaction with material expelled by its progenitor, it offers a great opportunity to constrain the uncertain evolutionary channels leading to low-luminosity supernovae. Our models indicate that the progenitor had a mass-loss rate of (6.0 +- 2.0) x 1e-4 Msun/yr (assuming a velocity of 150 km/s). The surface abundances of the progenitor are consistent with solar contents of He and CNO. If SN 2016b…
Recent extensive observations of Type Ia Supernovae (SNe Ia) have revealed the existence of a diversity of SNe Ia, including SNe Iax. We introduce two possible channels in the single degenerate scenario: 1) double detonations in sub-Chandrasekhar (Ch) mass CO white dwarfs (WDs), where a thin He envelope is developed with relatively low accretion rates after He novae even at low metallicities, and 2) carbon deflagrations in Ch-mass possibly hybrid C+O+Ne WDs, where WD winds occur at [Fe/H] ~ -2.5 at high accretion rates. These subclasses of SNe Ia are rarer than `normal' SNe Ia and do not affec…
The first generation of stars is quite unique. The absence of metals likely affects their formation, with current models suggesting a much more top-heavy initial mass fraction than what we observe today, and some of their other properties, such as rotation rates and binarity, are largely unknown or constrained by direct observations. But even non-rotation single stars of a given mass will evolve quite differently due to the absence of the metals: the stars will mostly remain much more compact until their death, with the hydrogen-rich later reaching down ten teems deeper in radius then in moder…
The r-process nucleosynthesis in core-collapse supernovae (CC-SNe) is studied, with a focus on the explosion scenario induced by rotation and strong magnetic fields. Nucleosynthesis calculations are conducted based on magneto-hydrodynamical explosion models with a wide range of parameters for initial rotation and magnetic fields. The explosion models are classified in two different types: i.e., prompt-magnetic-jet and delayed-magnetic-jet, for which the magnetic fields of proto-neutron stars (PNSs) during collapse and the core-bounce are strong and comparatively moderate, respectively. Followi…
The recent detection of 60Fe in the cosmic rays provides conclusive evidence that there is a recently synthesized component (few MY) in the GCRs (Binns et al. 2016). In addition, these nuclei must have been synthesized and accelerated in supernovae near the solar system, probably in the Sco-Cen OB association subgroups, which are about 100 pc distant from the Sun. Recent theoretical work on the production of r-process nuclei appears to indicate that it is difficult for SNe to produce the solar system abundances relative to iron of r-process elements with high atomic number (Z), including the a…
Superlinear Type II Superluminous Supernovae 2017fck and 2019cmv: A Possible Origin from Interacting Thermonuclear Supernovae
University of Florida（佛罗里达大学）；Las Cumbres Observatory（拉斯坎伯斯天文台）；University of California, Santa Barbara（加州大学圣塔芭芭拉分校）；National Astronomical Observatory of Japan（日本国立天文台）；Monash University（莫纳什大学）；Tel Aviv University（特拉维夫大学）；CIFAR（加拿大先进研究院）；Shady Side Academy（阴影边学院）；University of California, San Diego（加州大学圣地亚哥分校）；University of California（加州大学）；University of Toronto（多伦多大学）
The most iron-deficient stars in the Milky Way provide important observational constraints on the nature of astrophysical objects that have enriched the primordial gas with heavy elements from which these stars were formed. Among them, the recently discovered iron-deficient star SMSS J031300.36-670839.3 shows a remarkable chemical composition with non-detection of iron ([Fe/H]$<-7.1$) and large enhancement of carbon and magnesium relative to calcium. We investigate the supernova yields of metal-free (Population III) stars to interpret the observed abundance pattern for this star. We report tha…
The explosion energy of thermonuclear (Type Ia) supernovae is derived from the difference in nuclear binding energy liberated in the explosive fusion of light 'fuel' nuclei, predominantly carbon and oxygen, into more tightly bound nuclear 'ash' dominated by iron and silicon group elements. The very same explosive thermonuclear fusion event is also one of the major processes contributing to the nucleosynthesis of the heavy elements, in particular the iron-group elements. For example, most of the iron and manganese in the sun and its planetary system were produced in thermonuclear supernovae. He…
Pristine stars with masses between ~140 and 260 M_sun are theoretically predicted to die as pair-instability supernovae. These very massive progenitors could come from Pop III stars in the early universe. We model the light curves and spectra of pair-instability supernovae over a range of masses and envelope structures. At redshifts of reionization z >= 6, we calculate the rates and detectability of pair-instability and core collapse supernovae, and show that with the James Webb Space Telescope, it is possible to determine the contribution of Pop III and Pop II stars toward reionization by con…
An erroneous interpretation of the hydrodynamical results led to an incorrect determination of the fallback masses in Ugliano et al. (2012), which also (on a smaller level) affects the neutron star masses provided in that paper. This problem was already addressed and corrected in the follow-up works by Ertl et al. (2015) and Sukhbold et al. (2015). Therefore, the reader is advised to use the new data of the latter two publications. In the remaining text of this Erratum we present the differences of the old and new fallback results in detail and explain the origin of the mistake in the original…
By using an average heavy nuclei model, the effects of the electron screening on electron capture (EC) in core-collapse supernovae are investigated. A one-dimension code based on the Ws15$M_{\sun}$ progenitor model is utilized to test the effects of electron screening during the collapsing process. The results show that, at high densities, the effects of EC on electron capture becomes significant. During the collapsing stage, the EC rate is decreased, the collapse timescale is prolonged and the leakage of the neutrino energy is increased. These effects lead to an appreciable decrease in the in…
Type Ia Supernovae (SNe Ia) form an observationally uniform class of stellar explosions, in that more luminous objects have smaller decline-rates. This one-parameter behavior allows SNe Ia to be calibrated as cosmological `standard candles', and led to the discovery of an accelerating Universe. Recent investigations, however, have revealed that the true nature of SNe Ia is more complicated. Theoretically, it has been suggested that the initial thermonuclear sparks are ignited at an offset from the centre of the white-dwarf (WD) progenitor, possibly as a result of convection before the explosio…
Almost since the beginning, massive stars and their resultant supernovae have played a crucial role in the Universe. These objects produce tremendous amounts of energy and new, heavy elements that enrich galaxies, encourage new stars to form and sculpt the shapes of galaxies we see today. The end of millions of years of massive star evolution and the beginning of hundreds or thousands of years of supernova evolution are separated by a matter of a few seconds, in which some of the most extreme physics found in the Universe causes the explosive and terminal disruption of the star. Key questions …
We present the nucleosynthesis of magneto-rotational supernovae (MR-SNe) including neutrino-driven and magneto-rotational-driven ejecta based, for the first time, on 2D simulations with accurate neutrino transport. The models analysed here have different rotation and magnetic fields, allowing us to explore the impact of these two key ingredients. The accurate neutrino transport of the simulations is critical to analyse the slightly neutron-rich and proton-rich ejecta that are similar to the, also neutrino-driven, ejecta in standard supernovae. In the model with strong magnetic field, the r-pro…
Type Ibn Supernovae (SNe Ibn) show signatures of strong interaction between the SN ejecta and hydrogen-poor circumstellar matter (CSM). Deriving the ejecta and CSM properties of SNe Ibn provides a great opportunity to study the final evolution of massive stars. In the present work, we present a light curve (LC) model for the ejecta-CSM interaction, taking into account the processes in which the high-energy photons originally created at the forward and reverse shocks are converted to the observed emission in the optical. The model is applied to a sample of SNe Ibn and `SN Ibn' rapidly evolving …
Type IIP supernovae (SNe IIP) are the most common class of core-collapse SNe. They often show rapid increase of polarization degree in the late phase. This time evolution is generally believed to originate from the emergence of an inner aspherical core, while an effect of polarized-scattered echoes by circumstellar (CS) dust around the SN may also substantially contribute to this polarization feature. In this study, we examine the effects of the scatted echoes on the SN polarization through radiative transfer simulations for various geometry and amount of CS dust. It has been found that asymme…
Binary stellar evolution has been studied as important pathway to initiate various transient events like supernovae (SNe). Although the common envelope (CE) in a binary, outcomes of the CE and conditions for the SN explosion during the CE phase are uncertain, it has been suggested that SN explosions can be triggered during the CE phase. In this work, we explore formation and evolution routes of carbon/oxygen (CO) WDs binaries in order to investigate mergers of CO WDs and cores of non-degenerate stars during the CE phase as possible origins for SNe under the core merger detonation (CMD) scenari…
We present the results of 3D hydrodynamic simulations of gamma-ray burst (GRB) jet emanating from a massive star with a particular focus on the formation of high-velocity quasi-spherical ejecta and the jet-induced chemical mixing. Recent early-time optical observations of supernovae associated with GRBs (e.g., GRB 171205A/SN 2017iuk) indicate a considerable amount of heavy metals in the high-velocity outer layers of the ejecta. Using our jet simulations, we show that the density and chemical structure of the outer ejecta implied by observations can be naturally reproduced by a powerful jet pen…
Massive stars (M> 10Msun) end their lives with spectacular explosions due to gravitational collapse. The collapse turns the stars into compact objects such as neutron stars and black holes with the ejection of cosmic rays and heavy elements. Despite the importance of these astrophysical events, the mechanism of supernova explosions has been an unsolved issue in astrophysics. This is because clarification of the supernova dynamics requires the full knowledge of nuclear and neutrino physics at extreme conditions, and large-scale numerical simulations of neutrino radiation hydrodynamics in multi-…
Core-collapse supernovae (CCSNe) are the explosions of massive stars following the collapse of the stars' iron cores. Poznanski (2013) has recently suggested an observational correlation between the ejecta velocities and the inferred masses of the red supergiant progenitors of type II-P explosions, which implies that the kinetic energy of the ejecta ($E_{\textrm{kin}}$) increases with the mass of the progenitor. I point out that the same conclusion can be reached from the model-free observed correlation between the ejected $^{56}$Ni masses ($M_{\textrm{Ni}}$) and the luminosities of the progen…
We investigated r-process nucleosynthesis in magneto-rotational supernovae, based on a new explosion mechanism induced by the magneto-rotational instability. A series of axisymmetric magneto-hydrodynamical simulations with detailed microphysics including neutrino heating is performed, numerically resolving the magneto-rotational instability. Neutrino-heating dominated explosions, enhanced by magnetic fields, showed mildly neutron-rich ejecta producing nuclei up to $A \sim 130$ (i.e. the weak r-process), while explosion models with stronger magnetic fields reproduce a solar-like r-process patte…
