scholarly journals r -process nucleosynthesis from matter ejected in binary neutron star mergers

2017 ◽  
Vol 96 (12) ◽  
Author(s):  
Luke Bovard ◽  
Dirk Martin ◽  
Federico Guercilena ◽  
Almudena Arcones ◽  
Luciano Rezzolla ◽  
...  
Keyword(s):  
Neutron Star ◽  
Binary Neutron Star ◽  
R Process

scholarly journals The Dynamics of Binary Neutron Star Mergers and GW170817

2020 ◽  
Vol 70 (1) ◽  
pp. 95-119 ◽  
Author(s):  
David Radice ◽  
Sebastiano Bernuzzi ◽  
Albino Perego
Keyword(s):  
Neutron Star ◽  
Nuclear Astrophysics ◽  
Theoretical Models ◽  
Physical Processes ◽  
Binary Neutron Star ◽  
Compact Binary ◽  
Open Questions ◽  
Binary Mergers ◽  
R Process ◽  
Process Elements

With the first observation of a binary neutron star merger through gravitational waves and light, GW170817, compact binary mergers have now taken the center stage in nuclear astrophysics. They are thought to be one of the main astrophysical sites of production of r-process elements, and merger observations have become a fundamental tool to constrain the properties of matter. Here, we review our current understanding of the dynamics of neutron star mergers in general and of GW170817 in particular. We discuss the physical processes governing the inspiral, merger, and postmerger evolution, and we highlight the connections between these processes, the dynamics, and the multimessenger observables. Finally, we discuss open questions and issues in the field and the need to address them through a combination of better theoretical models and new observations.

scholarly journals First Multimessenger Observations of a Neutron Star Merger

2021 ◽  
Vol 59 (1) ◽  
Author(s):  
Raffaella Margutti ◽  
Ryan Chornock
Keyword(s):  
Neutron Star ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Near Infrared ◽  
Annual Review ◽  
Publication Date ◽  
Wave Source ◽  
Binary Neutron Star ◽  
Dense Nuclear Matter ◽  
R Process

We describe the first observations of the same celestial object with gravitational waves and light. ▪ GW170817 was the first detection of a neutron star merger with gravitational waves. ▪ The detection of a spatially coincident weak burst of gamma-rays (GRB 170817A) 1.7 s after the merger constituted the first electromagnetic detection of a gravitational wave source and established a connection between at least some cosmic short gamma-ray bursts (SGRBs) and binary neutron star mergers. ▪ A fast-evolving optical and near-infrared transient (AT 2017gfo) associated with the event can be interpreted as resulting from the ejection of ∼0.05 M⊙ of material enriched in r-process elements, finally establishing binary neutron star mergers as at least one source of r-process nucleosynthesis. ▪ Radio and X-ray observations revealed a long-rising source that peaked ∼[Formula: see text] after the merger. Combined with the apparent superluminal motion of the associated very long baseline interferometry source, these observations show that the merger produced a relativistic structured jet whose core was oriented ≈20 deg from the line of sight and with properties similar to SGRBs. The jet structure likely results from interaction between the jet and the merger ejecta. ▪ The electromagnetic and gravitational wave information can be combined to produce constraints on the expansion rate of the Universe and the equation of state of dense nuclear matter. These multimessenger endeavors will be a major emphasis for future work. Expected final online publication date for the Annual Review of Astronomy and Astrophysics, Volume 59 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals Observations of GW170817 by DESGW and the DECam GW-EM Collaboration

2017 ◽  
Vol 13 (S338) ◽  
pp. 72-79
Author(s):  
James Annis
Keyword(s):  
Star Formation ◽  
Neutron Star ◽  
Spatial Localization ◽  
Star Formation History ◽  
Optical Counterpart ◽  
X Ray ◽  
Binary Neutron Star ◽  
Formation History ◽  
R Process ◽  
High Cadence

AbstractOn August 17, 2017 LIGO/Virgo detected a binary neutron star via gravitational waves. We observed 70 sq-degrees in the LIGO/Virgo spatial localization with the DECam on the 4m Blanco telescope covering 80% of the final map. Our group independently discovered an optical counterpart in NGC 4993. We searched our entire imaged region: the object in NGC 4993 was the only viable candidate. Our observations of NGC4993 show complicated morphology but simple star formation history. Our x-ray and radio observations indicate an off-axis jet as afterglow. Our high-cadence optical and infrared spectra show a source that must be described by at least two components, one of which is dominated by the r-process nucleosynthesis elements characteristic of a kilonova. Our modeling of the light curve demonstrates such a model in which 0.05 M⊙ of material is ejected from the system. Finally, we discuss the first standard siren measurement of H0.

scholarly journals Neutron star mergers and rare core-collapse supernovae as sources of r-process enrichment in simulated galaxies

2020 ◽  
Vol 494 (4) ◽  
pp. 4867-4883 ◽  
Author(s):  
Freeke van de Voort ◽  
Rüdiger Pakmor ◽  
Robert J J Grand ◽  
Volker Springel ◽  
Facundo A Gómez ◽  
...  
Keyword(s):  
Neutron Star ◽  
Milky Way ◽  
Small Variation ◽  
Abundance Ratio ◽  
Core Collapse ◽  
Binary Neutron Star ◽  
Low Metallicity ◽  
Process Event ◽  
R Process ◽  
Process Elements

ABSTRACT We use cosmological, magnetohydrodynamical simulations of Milky Way-mass galaxies from the Auriga project to study their enrichment with rapid neutron capture (r-process) elements. We implement a variety of enrichment models from both binary neutron star mergers and rare core-collapse supernovae. We focus on the abundances of (extremely) metal-poor stars, most of which were formed during the first ∼Gyr of the Universe in external galaxies and later accreted on to the main galaxy. We find that the majority of metal-poor stars are r-process enriched in all our enrichment models. Neutron star merger models result in a median r-process abundance ratio, which increases with metallicity, whereas the median trend in rare core-collapse supernova models is approximately flat. The scatter in r-process abundance increases for models with longer delay times or lower rates of r-process-producing events. Our results are nearly perfectly converged, in part due to the mixing of gas between mesh cells in the simulations. Additionally, different Milky Way-mass galaxies show only small variation in their respective r-process abundance ratios. Current (sparse and potentially biased) observations of metal-poor stars in the Milky Way seem to prefer rare core-collapse supernovae over neutron star mergers as the dominant source of r-process elements at low metallicity, but we discuss possible caveats to our models. Dwarf galaxies that experience a single r-process event early in their history show highly enhanced r-process abundances at low metallicity, which is seen both in observations and in our simulations. We also find that the elements produced in a single event are mixed with ≈108 M⊙ of gas relatively quickly, distributing the r-process elements over a large region.

scholarly journals Fission fragment distributions and their impact on the r -process nucleosynthesis in neutron star mergers

2021 ◽  
Vol 103 (2) ◽  
Author(s):  
J.-F. Lemaître ◽  
S. Goriely ◽  
A. Bauswein ◽  
H.-T. Janka
Keyword(s):  
Neutron Star ◽  
Fission Fragment ◽  
R Process

scholarly journals Waveform systematics in the gravitational-wave inference of tidal parameters and equation of state from binary neutron-star signals

2021 ◽  
Vol 103 (12) ◽  
Author(s):  
Rossella Gamba ◽  
Matteo Breschi ◽  
Sebastiano Bernuzzi ◽  
Michalis Agathos ◽  
Alessandro Nagar
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Gravitational Wave ◽  
Binary Neutron Star

scholarly journals 3D magnetized jet break-out from neutron-star binary merger ejecta: afterglow emission from the jet and the ejecta

2021 ◽  
Vol 502 (2) ◽  
pp. 1843-1855
Author(s):  
Antonios Nathanail ◽  
Ramandeep Gill ◽  
Oliver Porth ◽  
Christian M Fromm ◽  
Luciano Rezzolla
Keyword(s):  
Neutron Star ◽  
Thermal Emission ◽  
Opening Angle ◽  
Hollow Core ◽  
Binary Neutron Star ◽  
Vlbi Observations ◽  
Superluminal Motion ◽  
General Relativistic ◽  
Star Binary ◽  
Magnetohydrodynamic Simulations

ABSTRACT We perform 3D general-relativistic magnetohydrodynamic simulations to model the jet break-out from the ejecta expected to be produced in a binary neutron-star merger. The structure of the relativistic outflow from the 3D simulation confirms our previous results from 2D simulations, namely, that a relativistic magnetized outflow breaking out from the merger ejecta exhibits a hollow core of θcore ≈ 4°, an opening angle of θjet ≳ 10°, and is accompanied by a wind of ejected matter that will contribute to the kilonova emission. We also compute the non-thermal afterglow emission of the relativistic outflow and fit it to the panchromatic afterglow from GRB170817A, together with the superluminal motion reported from VLBI observations. In this way, we deduce an observer angle of $\theta _{\rm obs}= 35.7^{\circ \, \, +1.8}_{\phantom{\circ \, \, }-2.2}$. We further compute the afterglow emission from the ejected matter and constrain the parameter space for a scenario in which the matter responsible for the thermal kilonova emission will also lead to a non-thermal emission yet to be observed.

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