Origin of the heavy elements in binary neutron-star mergers from a gravitational-wave event

By D. Kasen, B. Metzger, J. Barnes, E. Quataert, E. Ramirez-Ruiz. Nature, 2017

877 citations recorded by the source corpus.

The cosmic origin of elements heavier than iron has long been uncertain. Theoretical modelling shows that the matter that is expelled in the violent merger of two neutron stars can assemble into heavy elements such as gold and platinum in a process known as rapid neutron capture (r-process) nucleosynthesis. The radioactive decay of isotopes of the heavy elements is predicted to power a distinctive thermal glow (a ‘kilonova’). The discovery of an electromagnetic counterpart to the gravitational-wave source GW170817 represents the first opportunity to detect and scrutinize a sample of freshly synthesized r-process elements. Here we report models that predict the electromagnetic emission of kilonovae in detail and enable the mass, velocity and composition of ejecta to be derived from observations. We compare the models to the optical and infrared radiation associated with the GW170817 event to argue that the observed source is a kilonova. We infer the presence of two distinct components of ejecta, one composed primarily of light (atomic mass number less than 140) and one of heavy (atomic mass number greater than 140) r-process elements. The ejected mass and a merger rate inferred from GW170817 imply that such mergers are a dominant mode of r-process production in the Universe.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/1ffcbb6ace8f59dcca8b486cec0da699652feee2

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In Astronomy and Astrophysics

1. B. Metzger
2. E. Berger
3. E. Quataert
4. D. Kasen
5. David Radice
6. R. Fern'andez
7. T. Thompson
8. Luke F. Roberts

In Nuclear and High Energy Physics

1. B. Metzger
2. D. Kasen
3. Hans-Thomas Janka
4. E. Quataert
5. David Radice
6. T. Thompson
7. E. Berger
8. R. Fern'andez

Citations in the corpus

• The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. IV. Detection of Near-infrared Signatures of r-process Nucleosynthesis with Gemini-South (2017, background): “While the treatment of the atomic data remains highly uncertain, there is general agreement that this spectral distinction is a unique signature of material with enhanced r-process abundances (Kasen et al. 2017; Tanaka et al. 2017; Wollaeger et al. 2017).”
• Three-dimensional GRMHD Simulations of Neutrino-cooled Accretion Disks from Neutron Star Mergers (2017, background): “0.25) expanding at a lower velocity v ≈ 0.1 c (e.g. Kasen et al. 2017; Cowperthwaite et al. 2017; Tanvir et al. 2017; Shappee et al. 2017; Kilpatrick et al. 2017; Kasliwal et al. 2017; Nicholl et al. 2017; Chornock et al. 2017; Drout et al. 2017; Mc- Cully et al. 2017; Tanvir et al. 2017; Villar et…”
• A Magnetar Origin for the Kilonova Ejecta in GW170817 (2018, background): “…these give best-fit values for the ejecta masses and mean velocities of the blue and red components of M M v c2 10 , 0.25blue 2 blue» ´ »- and Mred≈0.05Me, vred≈0.1 c, respectively (e.g., Cowperthwaite et al. 2017; Drout et al. 2017; Kasen et al. 2017; Perego et al. 2017; Villar et al. 2017).”
• Multi-messenger observations of a binary neutron star merger (2017, methodology): “…features indicated that the source had physical properties similar to models of kilonovae (e.g., Metzger et al. 2010; Kasen et al. 2013; Barnes & Kasen 2013; Tanaka & Hotokezaka 2013; Grossman et al. 2014; Metzger & Fernández 2014; Barnes et al. 2016; Tanaka 2016; Kasen et al. 2017; Metzger 2017).”
• Constraints on the neutron star equation of state from AT2017gfo using radiative transfer simulations (2018, methodology): “The model provided in Kasen et al. (2017) and described above is produced on a grid with ejecta masses Mej[M ] = 0.001, 0.0025, 0.005, 0.0075, 0.01, 0.25, 0.05, and 0.1, ejecta velocities vej[c] = 0.03, 0.05, 0.1, 0.2, and 0.3, and mass fraction of lanthanides Xlan = 0, 10−5, 10−4, 10−3, 10−2, and…”
• Stringent constraints on neutron-star radii from multimessenger observations and nuclear theory (2019, methodology): “ find R= 12:2+1:0 0:8 0:2km. Coughlin et al. [2] performed joint electromagnetic and GW parameter estimation, directly fitting the kilonova photometry using results from radiative transfer calculations [8] and numerical relativity simulations, along with modeling of the associated gamma-ray burst GRB1”
• Science case for the Einstein telescope (2019, background): “of the heaviest elements through r-process nucleosynthesis [12–15]; the observation of tens of BH-BH coalescences has revealed a previously unknown population of stellar-mass BHs, much heavier than those detected through the observation of X-ray binaries [16], and has shown that BH-BH binaries exist”
• The Zwicky Transient Facility: Science Objectives (2019, background): “…and spectroscopy coupled with reliable rate estimates will quantify how prolific a site of r-process nucleosynthesis they are and whether they can explain the observed Solar abundance of heavy elements (e.g., Drout et al. 2017; Kasliwal et al. 2017; Kasen et al. 2017; Hotokezaka et al. 2018).”
• Long-term GRMHD simulations of neutron star merger accretion discs: implications for electromagnetic counterparts (2018, background): “While the total ejecta mass in our GRMHD model (0.013M ) is lower than that inferred from the kilonova associated with GW170817 (e.g., Kasen et al. 2017), our initial disk mass is also lower than the value expected for GW170817.”