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We performed general relativistic, long-term, axisymmetric neutrino radiation hydrodynamics simulations for the remnant formed after the binary neutron star merger, which consist of a massive neutron star and a torus surrounding it. As an…

High Energy Astrophysical Phenomena · Physics 2018-07-25 Sho Fujibayashi , Yuichiro Sekiguchi , Kenta Kiuchi , Masaru Shibata

We perform a comparative analysis of nucleosynthesis yields from binary neutron star (BNS) mergers, black hole-neutron star (BHNS) mergers, and core-collapse supernovae (CCSNe) with the goal of determining which are the most dominant…

High Energy Astrophysical Phenomena · Physics 2023-08-30 Nick Ekanger , Mukul Bhattacharya , Shunsaku Horiuchi

A long-standing scientific puzzle has been to explain the origin of the heaviest elements in the Universe and, more particularly, the production of the elements heavier than iron up to uranium. The rapid neutron capture process (or…

High Energy Astrophysical Phenomena · Physics 2023-03-14 Ina K. B. Kullmann

We investigate the dynamics and electromagnetic (EM) signatures of neutron star-neutron star (NS-NS) or neutron star-black hole (NS-BH) merger ejecta that occurs in the accretion disk of an active galactic nucleus (AGN). We find that the…

High Energy Astrophysical Phenomena · Physics 2022-12-07 Jia Ren , Ken Chen , Yun Wang , Zi-Gao Dai

We use results from long-time core-collapse supernovae simulations to investigate the impact of the late time evolution of the ejecta and of the nuclear physics input on the calculated r-process abundances. Based on the latest…

Solar and Stellar Astrophysics · Physics 2011-05-13 A. Arcones , G. Martinez-Pinedo

Neutrinos emitted in the coalescence of two neutron stars affect the dynamics of the outflow ejecta and the nucleosynthesis of heavy elements. In this work, we analyze the neutrino emission properties and the conditions leading to the…

High Energy Astrophysical Phenomena · Physics 2020-11-16 Manu George , Meng-Ru Wu , Irene Tamborra , Ricard Ardevol-Pulpillo , Hans-Thomas Janka

We explore heavy-element nucleosynthesis by rapid neutron capture (r-process) in the decompressing ejecta from the surface of a neutron star. The decompression is triggered by a violent phase transition to strange quark matter (quark-nova…

Nuclear Theory · Physics 2009-03-19 Prashanth Jaikumar , Bradley S. Meyer , Kaori Otsuki , Rachid Ouyed

New viscous neutrino-radiation hydrodynamics simulations are performed for accretion disks surrounding a spinning black hole with low mass $3M_\odot$ and dimensionless spin 0.8 or 0.6 in full general relativity, aiming at modeling the…

High Energy Astrophysical Phenomena · Physics 2020-04-29 Sho Fujibayashi , Masaru Shibata , Shinya Wanajo , Kenta Kiuchi , Koutarou Kyutoku , Yuichiro Sekiguchi

We investigate the long-term evolution of black hole accretion disks formed in neutron star mergers. These disks expel matter that contributes to an $r$-process kilonova, and can produce relativistic jets powering short gamma-ray bursts.…

High Energy Astrophysical Phenomena · Physics 2018-11-07 Rodrigo Fernández , Alexander Tchekhovskoy , Eliot Quataert , Francois Foucart , Daniel Kasen

Rapid neutron capture process (r-process) elements have been detected in a large fraction of metal-poor halo stars, with abundances relative to iron (Fe) that vary by over two orders of magnitude. This scatter is reduced to less than a…

Astrophysics of Galaxies · Physics 2019-08-16 B. Wehmeyer , C. Frohlich , B. Côté , M. Pignatari , F. -K. Thielemann

We present a first simulation of the post-merger evolution of a black hole-neutron star binary in full general relativity using an energy-integrated general relativistic truncated moment formalism for neutrino transport. We describe our…

The majority of existing results for the kilonova (or macronova) emission from material ejected during a neutron-star (NS) merger is based on (quasi-)one-zone models or manually constructed toy-model ejecta configurations. In this study we…

High Energy Astrophysical Phenomena · Physics 2022-05-06 Oliver Just , Ina Kullmann , Stephane Goriely , Andreas Bauswein , Hans-Thomas Janka , Christine E. Collins

Neutron star mergers are today considered a major production site for rapid neutron capture elements. While the bulk of the matter escapes at fast, but non-relativistic velocities (${\sim} 0.2\,c$), a small amount of the dynamically ejected…

High Energy Astrophysical Phenomena · Physics 2026-05-18 Lukas Schnabel , Stephan Rosswog , Friedrich-Karl Thielemann , Moritz Reichert

Coalescence of neutron stars gives rise to kilonova, thermal emission powered by radioactive decays of freshly synthesized r-process nuclei. Although observational properties are largely affected by bound-bound opacities of r-process…

High Energy Astrophysical Phenomena · Physics 2020-06-10 Masaomi Tanaka , Daiji Kato , Gediminas Gaigalas , Kyohei Kawaguchi

We present 3D general-relativistic neutrino-radiation hydrodynamics simulations of two asymmetric binary neutron star mergers producing long-lived neutron stars remnants and spanning a fraction of their cooling time scale. The mergers are…

High Energy Astrophysical Phenomena · Physics 2025-08-28 Sebastiano Bernuzzi , Fabio Magistrelli , Maximilian Jacobi , Domenico Logoteta , Albino Perego , David Radice

We present a systematic numerical relativity study of the mass ejection and the associated electromagnetic transients and nucleosynthesis from binary neutron star (NS) mergers. We find that a few $10^{-3}\, M_\odot$ of material are ejected…

High Energy Astrophysical Phenomena · Physics 2019-06-03 David Radice , Albino Perego , Kenta Hotokezaka , Steven A. Fromm , Sebastiano Bernuzzi , Luke F. Roberts

A compact accretion disk may be formed in the merger of two neutron stars or of a neutron star and a stellar-mass black hole. Outflows from such accretion disks have been identified as a major site of rapid neutron-capture (r-process)…

High Energy Astrophysical Phenomena · Physics 2021-06-30 Xinyu Li , Daniel M. Siegel

As a follow-up study of our previous work, numerical-relativity simulations for seconds-long black hole-neutron star mergers are performed for a variety of setups. Irrespective of the initial and symmetry conditions, we find qualitatively…

High Energy Astrophysical Phenomena · Physics 2023-06-14 Kota Hayashi , Kenta Kiuchi , Koutarou Kyutoku , Yuichiro Sekiguchi , Masaru Shibata

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…

High Energy Astrophysical Phenomena · Physics 2018-12-27 David Radice , Albino Perego , Kenta Hotokezaka , Sebastiano Bernuzzi , Steven A. Fromm , Luke F. Roberts

A multi-messenger, black hole (BH) - neutron star (NS) merger event still remains to be detected. The tidal (dynamical) ejecta from such an event, thought to produce a kinonova, is concentrated in the equatorial plane and occupies only part…

High Energy Astrophysical Phenomena · Physics 2023-09-08 Yan Li , Rong-Feng Shen