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-process nucleosynthesis from matter ejected in binary neutron star mergers

Bovard, Luke; Martin, Dirk; Guercilena, Federico; Arcones, Almudena; Rezzolla, Luciano; Korobkin, Oleg

doi:10.1103/physrevd.96.124005

Cited by 187 publications

(187 citation statements)

References 138 publications

(219 reference statements)

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“…If a part of the ejecta component is produced by getting energy in a far region, e.g., by angular momentum transport due to tidal torque exerted by the central object and neutrino heating, the ejecta mass could be underestimated for the simulations with a small computational region (see also a discussion of Ref. [115]). It should be also noted that these groups estimated the ejecta mass before the spacetime in a corresponding region relaxes to a stationary state because the typical velocity of the dynamical ejecta is v ej ∼ 0.2c-0.25c, i.e., ≈ 60-75 km/ms, and the ejecta goes through the outer boundaries or the surface of the flux integral at 10 ms after the onset of merger.…”

Section: Discussionmentioning

confidence: 99%

Modeling GW170817 based on numerical relativity and its implications

et al. 2017

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Gravitational-wave observation together with a large number of electromagnetic observations shows that the source of the latest gravitational-wave event, GW170817, detected primarily by advanced LIGO, is the merger of a binary neutron star. We attempt to interpret this observational event based on our results of numerical-relativity simulations performed so far paying particular attention to the optical and infra-red observations. We finally reach a conclusion that this event is described consistently by the presence of a long-lived hypermassive or supramassive neutron star as the merger remnant, because (i) significant contamination by lanthanide elements along our line of sight to this source can be avoided by the strong neutrino irradiation from it and (ii) it could play a crucial role to produce an ejecta component of appreciable mass with fast motion in the postmerger phase. We also point out that (I) the neutron-star equation of state has to be sufficiently stiff (i.e., the maximum mass of cold spherical neutron stars, Mmax, has to be appreciably higher than 2M ) in order that a long-lived massive neutron star can be formed as the merger remnant for the binary systems of GW170817, for which the initial total mass is 2.73M and (II) no detection of relativistic optical counterpart suggests a not-extremely high value of Mmax approximately as 2.15-2.25M .

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Section: Discussionmentioning

confidence: 99%

Modeling GW170817 based on numerical relativity and its implications

et al. 2017

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“…Hypermassive massive neutron star (HMNS): -Second is the case in which a hypermassive NS (HMNS) is formed temporarily and the remnant collapses to a BH after surviving for more than 10 ms. For this case, mass of the dynamical ejecta and the remnant torus can be massive up to ∼ 0.001-0.01 M and ∼ 0.1 M , respectively Bauswein et al 2013;Sekiguchi et al 2015Sekiguchi et al , 2016Radice et al 2016;Dietrich et al 2017;Bovard et al 2017). Y e of the dynamical ejecta can be raised are the total mass of the binary, maximum mass of a rigidly rotating NS, threshold total mass for the prompt collapse, dynamical ejecta mass, remnant torus mass, and the timescale for the remnant to collapse to a BH, respectively.…”

Section: Variety In the Ejecta Propertiesmentioning

confidence: 95%

Diversity of Kilonova Light Curves

Kawaguchi

Shibata

Tanaka

2020

ApJ

141

151

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We perform radiative transfer simulations for kilonova in various situations, including the cases of prompt collapse to a black hole from neutron-star mergers, high-velocity ejecta possibly accelerated by magnetars, and a black hole-neutron star merger. Our calculations are done employing ejecta profiles predicted by numerical-relativity simulations and a new line list for all the r-process elements. We found that (i) the optical emission for binary neutron stars promptly collapsing to a black hole would be fainter by 1-2 mag than that found in GW170817, while the infrared emission could be as bright as that in GW170817 if the post-merger ejecta is as massive as ≈ 0.01 M ; (ii) the kilonova would be brighter than that observed in GW170817 for the case that the ejecta is highly accelerated by the electromagnetic energy injection from the remnant, but it would decline rapidly and the magnitude would become fainter than in GW170817 within a few days; (iii) the optical emission from a black hole-neutron star merger ejecta could be as bright as that observed in GW170817 for the case that sufficiently large amount of matter is ejected ( 0.02 M ), while the infrared brightness would be brighter by 1-2 mag at the same time. We show that the difference in the ejecta properties would be imprinted in the differences in the peak brightness and time of peak. This indicates that we may be able to infer the type of the central engine for kilonovae by observation of the peak in the multiple band.

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“…The first peak elements are predominantly produced for Y e 0.35. Numerical simulation of dynamical ejecta (Freiburghaus et al 1999;Bauswein et al 2013;Sekiguchi et al 2015;Foucart et al 2016;Radice et al 2016Radice et al , 2018Bovard et al 2017) and disk wind (Fernández & Metzger 2013;Fernández et al 2015;Metzger & Fernández 2014;Perego et al 2014;Just et al 2015;Fujibayashi et al 2017;Siegel & Metzger 2018) show that Y e is broadly distributed in a certain atomic number range and the abundance patterns are typically consistent with the solar pattern with a minimum atomic mass of A min ∼ 80-120. Note, however, that lighter elements are synthesized more when neutrino absorption significantly changes the electron fraction.…”

Section: Ejecta Mass Estimate Based On the Katz Integralmentioning

confidence: 96%

Radioactive Heating Rate of r-process Elements and Macronova Light Curve

Hotokezaka

Nakar

2020

ApJ

100

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We study the heating rate of r-process nuclei and thermalization of decay products in neutron star merger ejecta and macronova (kilonova) light curves. Thermalization of charged decay products, i.e., electrons, α-particles, and fission fragments is calculated according to their injection energy. The γ-ray thermalization processes are also properly calculated by taking the γ-ray spectrum of each decay into account. We show that the β-decay heating rate at later times approaches a powerlaw decline as ∝ t −2.8 , which agrees with the result of Waxman et al. (2019). We present a new analytic model to calculate macronova light curves, in which the density structure of the ejecta is accounted for. We demonstrate that the observed bolometric light curve and temperature evolution of the macronova associated with GW170817 are reproduced well by the β-decay heating rate with the solar r-process abundance pattern. We interpret the break in the observed bolometric light curve around a week as a result of the diffusion wave crossing a significant part of the ejecta rather than a thermalization break. We also show that the time-weighted integral of the bolometric light curve (Katz integral) is useful to provide an estimate of the total r-process mass from the observed data, which is independent of the highly uncertain radiative transfer. For the macronova in GW170817, the ejecta mass is robustly estimated as ≈ 0.05M for A min ≤ 72 and 85 ≤ A min ≤ 130 with the solar r-process abundance pattern. The code for computation of the heating rate and light curve for given initial nuclear abundances is publicly available.

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

Cited by 187 publications

References 138 publications

Modeling GW170817 based on numerical relativity and its implications

Modeling GW170817 based on numerical relativity and its implications

Diversity of Kilonova Light Curves

Radioactive Heating Rate of r-process Elements and Macronova Light Curve

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