Abstract We present a systematic numerical relativity study of the mass ejection and associated electromagnetic transients nucleosynthesis from binary neutron star (NS) mergers. find that few 10 −3 M ⊙ material is ejected dynamically during The amount properties these outflows depend on parameters NS equation state (EOS). A small fraction ejecta, typically ∼10 −6 , accelerated by shocks formed shortly after merger to velocities larger than 0.6 c produces bright radio flares timescales weeks,...

We present fully general-relativistic simulations of binary neutron star mergers with a temperature and composition dependent nuclear equation state. study the dynamical mass ejection from both quasi-circular dynamical-capture eccentric mergers. systematically vary level our treatment microphysics to isolate effects neutrino cooling heating we compute nucleosynthetic yields ejecta. find that binaries can eject significantly more material than generate bright infrared radio emission. In all...

r-process nucleosynthesis in material ejected during neutron star mergers may lead to radioactively powered transients called kilonovae. The timescale and peak luminosity of these depend on the composition ejecta, which determines local heating rate from nuclear decays opacity. Kasen et al. Tanaka & Hotokezaka pointed out that lanthanides can drastically increase opacity outflows. We use new general-purpose reaction network SkyNet carry a parameter study for range initial electron fractions...

Neutron star mergers are among the most promising sources of gravitational waves for advanced ground-based detectors. These also expected to power bright electromagnetic signals, in form short gamma-ray bursts, infrared/optical transients powered by r-process nucleosynthesis neutron-rich material ejected merger, and radio emission from interaction that ejecta with interstellar medium. Simulations these fully general relativistic codes critical understand merger postmerger wave signals their...

We investigate the nucleosynthesis of heavy elements in winds ejected by accretion disks formed neutron star mergers. compute element formation disk outflows from hypermassive (HMNS) remnants variable lifetime, including effect angular momentum transport evolution. employ long-term axisymmetric hydrodynamic simulations to model ejecta, and r-process with tracer particles using a nuclear reaction network containing $\sim 8000$ species. find that previously known strong correlation between...

The possibility that long tidal tails formed during compact object mergers may power optical transients through the decay of freshly synthesized r-process material is investigated. Precise modeling merger dynamics allows for a realistic determination thermodynamic conditions in ejected debris. results hydrodynamic and full nuclear network calculations are combined to calculate resultant abundances heating by their decays. subsequent homologous structure mapped into radiative transfer code...

Previous work on neutrino emission from proto-neutron stars which employed full solutions of the Boltzmann equation showed that average energies emitted electron neutrinos and antineutrinos are closer to one another than predicted by older, more approximate work. This in turn implied driven wind is proton rich during its entire life, precluding $r$-process nucleosynthesis synthesis Sr, Y, Zr. relied charged current interaction rates appropriate for a free nucleon gas. Here, it shown detail...

We present the SuperNova Explosion Code (SNEC), an open-source Lagrangian code for hydrodynamics and equilibrium-diffusion radiation transport in expanding envelopes of supernovae. Given a model progenitor star, explosion energy, amount distribution radioactive nickel, SNEC generates bolometric light curve, as well curves different broad bands assuming blackbody emission. As first application SNEC, we consider explosions grid 15 M⊙ (at zero-age main sequence, ZAMS) stars whose hydrogen are...

We report on a set of long-term general-relativistic three-dimensional (3D) multi-group (energy-dependent) neutrino-radiation hydrodynamics simulations core-collapse supernovae. employ full 3D two-moment scheme with the local M1 closure, three neutrino species, and 12 energy groups per species. With this, we follow post-core-bounce evolution core nonrotating $27$-$M_\odot$ progenitor in unconstrained octant symmetry for $\gtrsim$$ 380\,\mathrm{ms}$. find development an asymmetric runaway...

We investigate r-process nucleosynthesis in three-dimensional (3D) general-relativistic magnetohydrodynamic simulations of rapidly rotating strongly magnetized core collapse. The include a microphysical finite-temperature equation state and leakage scheme that captures the overall energetics lepton number exchange due to postbounce neutrino emission absorption. track composition ejected material using nuclear reaction network SkyNet. Our results show 3D dynamics magnetorotational...

We present a first simulation of the post-merger evolution black hole-neutron star binary in full general relativity using an energy-integrated relativistic truncated moment formalism for neutrino transport. describe our implementation and important tests code, before studying formation phase disk after merger. use as initial data existing merger neutron 1.4 solar mass with hole 7 dimensionless spin a/M=0.8. Comparing simpler leakage scheme treatment neutrinos, we find noticeable differences...

Compact binary mergers involving at least one neutron star are important sources of gravitational waves. To fully describe such mergers, however, requires not only general relativity but also nuclear physics, hydrodynamics, and neutrino transport. The paper by Foucart et al. marks a significant step in this direction showing the sensitivity observables to energy spectrum.

Although they are but a small fraction of the mass ejected in core-collapse supernovae, neutrino-driven winds (NDWs) from nascent proto-neutron stars (PNSs) have potential to contribute significantly supernova nucleosynthesis. In previous works, NDW has been implicated as possible source r-process and light p-process isotopes. this paper, we present time-dependent hydrodynamic calculations nucleosynthesis which include accurate weak interaction physics coupled full nuclear reaction network....

We model neutrino emission from a newly born neutron star subsequent to supernova explosion study its sensitivity the equation of state, opacities, and convective instabilities at high baryon density. find time period spatial extent over which convection operates is sensitive behavior nuclear symmetry energy above When ends within protoneutron star, there break in predicted that may be clearly observable.

We present a first study of the progenitor star dependence three-dimensional (3D) neutrino mechanism core-collapse supernovae. employ full 3D general-relativistic multi-group radiation-hydrodynamics and simulate post-bounce evolutions progenitors with zero-age main sequence masses $12$, $15$, $20$, $27$, $40\,M_\odot$. All progenitors, exception $12\,M_\odot$ star, experience shock runaway by end their simulations. In most cases, strongly asymmetric explosion will result. find three...

The equation of state (EOS) dense matter is an essential ingredient for numerical simulations core-collapse supernovae and neutron star mergers. properties near above nuclear saturation density are uncertain, which translates into uncertainties in astrophysical their multi-messenger signatures. Therefore, a wide range EOSs spanning the allowed interactions necessary determining sensitivity these phenomena signatures to variations input microphysics. We present new set finite temperature...

The merger of two neutron stars leaves behind a rapidly spinning hypermassive object whose survival is believed to depend on the maximum mass supported by nuclear equation state (EOS), angular momentum redistribution (magneto-)rotational instabilities, and spindown gravitational waves. high temperatures (∼5–40 MeV) prevailing in remnant may provide thermal pressure support that could increase its and, thus, life neutrino-cooling timescale. We investigate role remnants computing sequences...

We present results from the first large parameter study of neutron star mergers using fully general relativistic simulations with finite-temperature microphysical equations state and neutrino cooling. consider equal unequal-mass binaries drawn galactic population simulate each binary three different state. Our focus is on emission energy angular momentum in gravitational waves postmerger phase. find that emitted gravitational-wave $\sim$$10\,\mathrm{ms}$ life resulting hypermassive (HMNS)...

In this theoretical study of successful core-collapse supernovae, the authors provide a detailed model neutrino emission from different phases transition - explosion to proto-neutron star cooling late-time formation either neutron or black hole. They show that for supernova in Milky Way, these copiously produced neutrinos can be detected by current neutrino-detection experiments and used extract information about course event. The offers highly promising program make full use rare event as...

The next Milky Way supernova will be an epochal event in multimessenger astronomy, critical to tests of supernovae, neutrinos, and new physics. Realizing this potential depends on having realistic simulations core collapse. We investigate the neutrino predictions modern models (1-, 2-, 3-D) over first $\ensuremath{\simeq}1\text{ }\text{ }\mathrm{s}$, making detailed comparisons these each other SN 1987A data. Even with different methods inputs, generally agree other. However, even...

A new code for following the evolution and emissions of proto-neutron stars during first minute their lives is developed tested. The one dimensional, fully implicit, general relativistic. Multi-group, multi-flavor neutrino transport incorporated that makes use variable Eddington factors obtained from a formal solution static relativistic Boltzmann equation with linearized scattering terms. timescales emission spectral using are broadly consistent previous results. Unlike other recent...

We present a proof-of-concept study, based on numerical-relativity simulations, of how gravitational waves (GWs) from neutron star merger remnants can probe the nature matter at extreme densities. Phase transitions and extra degrees freedom emerge densities beyond those reached during inspiral, typically result in softening equation state (EOS). show that such physical effects change qualitative dynamics remnant evolution, but they are not identifiable as signature GW frequency, with...

During the merger of a black hole and neutron star, baryonic mass can become unbound from system. Because ejected material is extremely neutron-rich, r-process rapidly synthesizes heavy nuclides as expands cools. In this work, we map general relativistic models hole-neutron star (BHNS) mergers into Newtonian smoothed particle hydrodynamics (SPH) code follow evolution thermodynamics morphology ejecta until outflows homologous. We investigate how subsequent depends on our mapping procedure...

General-relativistic simulations of binary neutron star mergers with viscosity reveal a new outflow mechanism operating in unequal mass binaries on dynamical timescales and enabled by turbulent viscosity. These "viscous-dynamical" ejecta are launched during merger due to the thermalization exchange streams between secondary primary star. They characterized asymptotic velocities extending up ${\sim} 0.8\, c$, have masses that depend efficiency viscous mechanism. Depending unknown strength...