The relation between the observed mass distribution for compact stars and the mechanism for supernova explosions (original) (raw)
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Recycling of neutron stars in common envelopes and hypernova explosions
Monthly Notices of the Royal Astronomical Society, 2011
In this paper we propose a new plausible mechanism of supernova explosions specific to close binary systems. The starting point is the common envelope phase in the evolution of a binary consisting of a red super giant and a neutron star. As the neutron star spirals towards the center of its companion it spins up via disk accretion. Depending on the specific angular momentum of gas captured by the neutron star via the Bondi-Hoyle mechanism, it may reach millisecond periods either when it is still inside the common envelope or after it has merged with the companion core. The high accretion rate may result in strong differential rotation of the neutron star and generation of the magnetar-strength magnetic field. The magnetar wind can blow away the common envelope if its magnetic field is as strong as 10 15 G, and can destroy the entire companion if it is as strong as 10 16 G. The total explosion energy can be comparable to the rotational energy of a millisecond pulsar and reach 10 52 erg. However, only a small amount of 56 Ni is expected to be produced this way. The result is an unusual type-II supernova with very high luminosity during the plateau phase, followed by a sharp drop in brightness and a steep light-curve tail. The remnant is either a solitary magnetar or a close binary involving a Wolf-Rayet star and a magnetar. When this Wolf-Rayet star explodes this will be a third supernovae explosion in the same binary. c 0000 RAS arXiv:1012.4565v2 [astro-ph.HE]
The Angular Momenta of Neutron Stars and Black Holes as a Window on Supernovae
The Astrophysical Journal, 2011
It is now clear that a subset of supernovae display evidence for jets and are observed as gamma-ray bursts. The angular momentum distribution of massive stellar endpoints provides a rare means of constraining the nature of the central engine in core-collapse explosions. Unlike supermassive black holes, the spin of stellarmass black holes in X-ray binary systems is little affected by accretion, and accurately reflects the spin set at birth. A modest number of stellar-mass black hole angular momenta have now been measured using two independent X-ray spectroscopic techniques. In contrast, rotation-powered pulsars spin-down over time, via magnetic braking, but a modest number of natal spin periods have now been estimated. For both canonical and extreme neutron star parameters, statistical tests strongly suggest that the angular momentum distributions of black holes and neutron stars are markedly different. Within the context of prevalent models for core-collapse supernovae, the angular momentum distributions are consistent with black holes typically being produced in GRB-like supernovae with jets, and with neutron stars typically being produced in supernovae with too little angular momentum to produce jets via magnetohydrodynamic processes. It is possible that neutron stars are imbued with high spin initially, and rapidly spun-down shortly after the supernova event, but the available mechanisms may be inconsistent with some observed pulsar properties.
Two New Possible Mechanisms of Supernova-Like Explosions
Springer Proceedings in Physics, 2000
Primordial black holes (PBHs) of microscopical size can completely absorb neutron stars (NSs) and white dwarfs (WDs) for less than the Hubble time. NS absorption is accompanied by inverse URCA process giving rise to emission of antineutrino. However considerable part of these antineutrino fails to escape NS being drawn into the growing black hole by accreting NS matter. The final stage of dense WD absorption is accompanied by 10 51 erg neutrino burst able to ignite nuclear burning giving rise to supernova-like WD explosion.
ON THE INDUCED GRAVITATIONAL COLLAPSE OF A NEUTRON STAR TO A BLACK HOLE BY A TYPE Ib/c SUPERNOVA
The Astrophysical Journal, 2012
It is understood that the supernovae (SNe) associated with gamma-ray bursts (GRBs) are of Type Ib/c. The temporal coincidence of the GRB and the SN continues to represent a major enigma of Relativistic Astrophysics. We elaborate here, from the earlier paradigm, that the concept of induced gravitational collapse is essential to explain the GRB-SN connection. The specific case of a close (orbital period <1 hr) binary system composed of an evolved star with a neutron star (NS) companion is considered. We evaluate the accretion rate onto the NS of the material expelled from the explosion of the core progenitor as a Type Ib/c SN and give the explicit expression of the accreted mass as a function of the nature of the components and binary parameters. We show that the NS can reach, in a few seconds, critical mass and consequently gravitationally collapse to a black hole. This gravitational collapse process leads to the emission of the GRB.
The Expulsion of Stellar Envelopes in Core‐Collapse Supernovae
The Astrophysical Journal, 1999
We examine the relation between presupernova stellar structure and the distribution of ejecta in core-collapse supernovae of types Ib, Ic and II, under the approximations of adiabatic, spherically symmetric flow. We develop a simple yet accurate analytical formula for the velocity of the initial forward shock that traverses the stellar envelope. For material that does not later experience a strong reverse shock, the entropy deposited by this forward shock persists into the final, freely-expanding state. We demonstrate that the final density distribution can be approximated with simple models for the final pressure distribution, in a way that matches the results of simulations. Our results indicate that the distribution of density and radiation pressure in a star's ejecta depends on whether the outer envelope is radiative or convective, and if convective, on the composition structure of the star.
The Explosion Mechanism of Core-Collapse Supernovae: Progress in Supernova Theory and Experiments
Publications of the Astronomical Society of Australia, 2015
The explosion of core-collapse supernova depends on a sequence of events taking place in less than a second in a region of a few hundred kilometers at the center of a supergiant star, after the stellar core approaches the Chandrasekhar mass and collapses into a proto-neutron star, and before a shock wave is launched across the stellar envelope. Theoretical efforts to understand stellar death focus on the mechanism which transforms the collapse into an explosion. Progress in understanding this mechanism is reviewed with particular attention to its asymmetric character. We highlight a series of successful studies connecting observations of supernova remnants and pulsars properties to the theory of core-collapse using numerical simulations. The encouraging results from first principles models in axisymmetric simulations is tempered by new puzzles in 3D. The diversity of explosion paths and the dependence on the pre-collapse stellar structure is stressed, as well as the need to gain a better understanding of hydrodynamical and MHD instabilities such as SASI and neutrino-driven convection. The shallow water analogy of shock dynamics is presented as a comparative system where buoyancy effects are absent. This dynamical system can be studied numerically and also experimentally with a water fountain. The potential of this complementary research tool for supernova theory is analyzed. We also review its potential for public outreach in science museums.
The Neutron Star and Black Hole Initial Mass Function
The Astrophysical Journal, 1996
Using recently calculated models for massive stellar evolution and supernovae coupled to a model for Galactic chemical evolution, neutron star and black hole birth functions (number of neutron stars and black holes as a function of their mass) are determined for the Milky Way Galaxy. For those stars that explode as Type II supernovae, the models give birth functions that are bimodal with peaks at 1.27 and 1.76 M and average masses within those peaks of 1.28 and 1.73 M. For those stars that explode as Type Ib there is a narrower spread of remnant masses, the average being 1.32 M , and less evidence for bimodality. These values will be increased, especially in the more massive Type II supernovae, if signi cant accretion continues during the initial launching of the shock, and the number of heavier neutron stars could be depleted by black hole formation. The principal reason for the dichotomy in remnant masses for Type II is the di erence in the presupernova structure of stars above and below 19 M , the mass separating stars that burn carbon convectively from those that produce less carbon and burn radiatively. The Type Ib's and the lower mass group of the Type II's compare favorably with measured neutron star masses, and in particular to the Thorsett et al. (1993) determination of the average neutron star mass in 17 systems; 1.35 0.27 M. Variations in the exponent of a Salpeter initial mass function are shown not to a ect the locations of the two peaks in the distribution function, but do a ect their relative amplitudes. Sources of uncertainty, in particular placement of the mass cut and sensitivity to the explosion energy, are discussed, and estimates of the total number of neutron stars and black holes in the Galaxy are given. Accretion induced collapse should give a unique gravitational mass of 1.27 M , although this could increase if accretion onto the newly formed neutron star continues. A similar mass will typify stars in the 8 ' 11 M range (e.g., the Crab pulsar). The lightest neutron star produced is 1.15 M for the Type II models and 1.22 M for the Type Ib models. Altogether there are about 10 9 neutron stars in our Galaxy and a comparable number of black holes.
Theoretical Models for Supernovae
Supernovae: A Survey of Current Research, 1982
arc present* 1 enu a variety of topics discussed. Parti lar emphasis is I. NUCLEOSYNTHESIS IN SUPERNOVA!; The study of heavy elcuent production in supcrnovac lias a long and distinguished history, extending back to at least 1946 when Hoy 1e first suggested the synthesis of a solar set of iron isotopes by the "eprocess". Interestingly, the proposed ejection mechanism for this
2021
We investigate observable signatures of a first-order quantum chromodynamics (QCD) phase transition in the context of core collapse supernovae. To this end, we conduct axially symmetric numerical relativity simulations with multi-energy neutrino transport, using a hadron-quark hybrid equation of state (EOS). We consider four non-rotating progenitor models, whose masses range from 9.6 to 70M⊙. We find that the two less massive progenitor stars (9.6 and 11.2 M⊙) show a successful explosion, which is driven by the neutrino heating. They do not undergo the QCD phase transition and leave behind a neutron star (NS). As for the more massive progenitor stars (50 and 70 M⊙), the proto-neutron star (PNS) core enters the phase transition region and experiences the second collapse. Because of a sudden stiffening of the EOS entering to the pure quark matter regime, a strong shock wave is formed and blows off the PNS envelope in the 50 M⊙ model. Consequently the remnant becomes a quark core surro...