scholarly journals Compact binary mergers as the origin of r-process elements in the Galactic halo

2014 ◽  
Author(s):  
Yuhri Ishimaru ◽  
Shinya Wanajo ◽  
Nikos Prantzos
Keyword(s):  
Galactic Halo ◽  
Compact Binary ◽  
Binary Mergers ◽  
R Process ◽  
Process Elements

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 Using failed supernovae to constrain the Galactic r-process element production

2019 ◽  
Vol 487 (2) ◽  
pp. 1745-1753 ◽  
Author(s):  
B Wehmeyer ◽  
C Fröhlich ◽  
B Côté ◽  
M Pignatari ◽  
F-K Thielemann
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Large Fraction ◽  
Capture Process ◽  
Compact Binary ◽  
Halo Stars ◽  
The Galaxy ◽  
Binary Mergers ◽  
R Process ◽  
Process Elements

ABSTRACT 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 factor of 3 in younger Galactic disc stars. The large scatter of r-process elements in the early Galaxy suggests that the r-process is made by rare events, like compact binary mergers and rare sub-classes of supernovae. Although being rare, neutron star mergers alone have difficulties to explain the observed enhancement of r-process elements in the lowest metallicity stars compared to Fe. The supernovae producing the two neutron stars already provide a substantial Fe abundance where the r-process ejecta from the merger would be injected. In this work we investigate another complementary scenario, where the r-process occurs in neutron star-black hole mergers in addition to neutron star mergers. Neutron star-black hole mergers would eject similar amounts of r-process matter as neutron star mergers, but only the neutron star progenitor would have produced Fe. Furthermore, a reduced efficiency of Fe production from single stars significantly alters the age–metallicity relation, which shifts the onset of r-process production to lower metallicities. We use the high-resolution [(20 pc)3/cell] inhomogeneous chemical evolution tool ‘ICE’ to study the outcomes of these effects. In our simulations, an adequate combination of neutron star mergers and neutron star-black hole mergers qualitatively reproduces the observed r-process abundances in the Galaxy.

Distribution of R- and S-Process Elements in the Galactic Halo

1988 ◽  
Vol 132 ◽  
pp. 501-506
Author(s):  
C. Sneden ◽  
C. A. Pilachowski ◽  
K. K. Gilroy ◽  
J. J. Cowan
Keyword(s):  
Heavy Element ◽  
Galactic Halo ◽  
Low Noise ◽  
Heavy Elements ◽  
Process Synthesis ◽  
Element Abundances ◽  
Halo Stars ◽  
Abundance Patterns ◽  
R Process ◽  
Process Elements

Current observational results for the abundances of the very heavy elements (Z>30) in Population II halo stars are reviewed. New high resolution, low noise spectra of many of these extremely metal-poor stars reveal general consistency in their overall abundance patterns. Below Galactic metallicities of [Fe/H] Ã −2, all of the very heavy elements were manufactured almost exclusively in r-process synthesis events. However, there is considerable star-to-star scatter in the overall level of very heavy element abundances, indicating the influence of local supernovas on element production in the very early, unmixed Galactic halo. The s-process appears to contribute substantially to stellar abundances only in stars more metal-rich than [Fe/H] Ã −2.

scholarly journals r-Process Nucleosynthesis from Compact Binary Mergers

2021 ◽  
pp. 1-56
Author(s):  
A. Perego ◽  
F. -K. Thielemann ◽  
G. Cescutti
Keyword(s):  
Compact Binary ◽  
Binary Mergers ◽  
R Process

scholarly journals Short-lived 244Pu points to compact binary mergers as sites for heavy r-process nucleosynthesis

2015 ◽  
Vol 11 (12) ◽  
pp. 1042-1042 ◽  
Author(s):  
Kenta Hotokezaka ◽  
Tsvi Piran ◽  
Michael Paul
Keyword(s):  
Compact Binary ◽  
Binary Mergers ◽  
R Process

scholarly journals Inhomogeneous Chemical Evolution of r-Process Elements in the Galactic Halo

2019 ◽  
pp. 91-96
Author(s):  
Benjamin Wehmeyer ◽  
Carla Fröhlich ◽  
Marco Pignatari ◽  
Friedrich-Karl Thielemann
Keyword(s):  
Chemical Evolution ◽  
Galactic Halo ◽  
R Process ◽  
Process Elements

The origin of r-process elements

Science ◽  
2021 ◽  
Vol 371 (6532) ◽  
pp. 901.18-903
Author(s):  
Keith T. Smith
Keyword(s):  
R Process ◽  
Process Elements

scholarly journals The AMBRE Project: r-process elements in the Milky Way thin and thick discs

2018 ◽  
Vol 619 ◽  
pp. A143 ◽  
Author(s):  
G. Guiglion ◽  
P. de Laverny ◽  
A. Recio-Blanco ◽  
N. Prantzos
Keyword(s):  
Chemical Evolution ◽  
Milky Way ◽  
Element Abundances ◽  
Thick Disc ◽  
Thin Disc ◽  
Solar Metallicity ◽  
R Process ◽  
Process Elements ◽  
Process Element ◽  
The Eu

Context. The chemical evolution of neutron capture elements in the Milky Way disc is still a matter of debate. There is a lack of statistically significant catalogues of such element abundances, especially those of the r-process. Aims. We aim to understand the chemical evolution of r-process elements in Milky Way disc. We focus on three pure r-process elements Eu, Gd, and Dy. We also consider a pure s-process element, Ba, in order to disentangle the different nucleosynthesis processes. Methods. We take advantage of high-resolution FEROS, HARPS, and UVES spectra from the ESO archive in order to perform a homogeneous analysis on 6500 FGK Milky Way stars. The chemical analysis is performed thanks to the automatic optimization pipeline GAUGUIN. We present abundances of Ba (5057 stars), Eu (6268 stars), Gd (5431 stars), and Dy (5479 stars). Based on the [α/Fe] ratio determined previously by the AMBRE Project, we chemically characterize the thin and the thick discs, and a metal-rich α-rich population. Results. First, we find that the [Eu/Fe] ratio follows a continuous sequence from the thin disc to the thick disc as a function of the metallicity. Second, in thick disc stars, the [Eu/Ba] ratio is found to be constant, while the [Gd/Ba] and [Dy/Ba] ratios decrease as a function of the metallicity. These observations clearly indicate a different nucleosynthesis history in the thick disc between Eu and Gd–Dy. The [r/Fe] ratio in the thin disc is roughly around +0.1 dex at solar metallicity, which is not the case for Ba. We also find that the α-rich metal-rich stars are also enriched in r-process elements (like thick disc stars), but their [Ba/Fe] is very different from thick disc stars. Finally, we find that the [r/α] ratio tends to decrease with metallicity, indicating that supernovae of different properties probably contribute differently to the synthesis of r-process elements and α-elements. Conclusions. We provide average abundance trends for [Ba/Fe] and [Eu/Fe] with rather small dispersions, and for the first time for [Gd/Fe] and [Dy/Fe]. This data may help to constrain chemical evolution models of Milky Way r- and s-process elements and the yields of massive stars. We emphasize that including yields of neutron-star or black hole mergers is now crucial if we want to quantitatively compare observations to Galactic chemical evolution models.

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