Binary neutron stars and production of heavy elements

Abstract

We show how merging neutron stars can be responsible for the production of heavy elements in the solar vicinity, in particular we study the evolution of the abundance of europium (Eu) relative to iron (Fe), as derived by stellar abundances measured in the Milky Way halo and disk stars. To do that, we adopt a detailed galactic chemical evolution model able to follow the evolution of the abundances of several chemical elements in the gas in our Galaxy. Merging of neutron stars after emission of gravitational waves has been observed for the first time in the event GW170817, which has represented the very first kilonova ever observed in the local universe. The production of heavy elements such as Eu (a typical r-process element) is discussed critically, pointing out that supernovae core collapse can produce some r-process elements but not enough to explain the solar abundance of Eu. On the other hand, the merging of compact objects can provide an amount of Eu much higher per single event than a single supernova. We discuss the various parameters involved, such as the merging timescales, the fraction of neutron star binaries and the present time rate of kilonova explosions. We compare model results with stellar data and conclude that merging of compact objects can be responsible for the bulk of Eu production in the Galaxy under some assumptions: (i) the merging binaries should have progenitors in the mass range 9–50\(M_{\odot }\), (ii) the merging timescales should be as short as 1 Myr and iii) each event should produce \(\sim 2 \times 10^{-6}M_{\odot }\). We also conclude that the Ligo/Virgo merging neutron star rate is consistent with our chemical evolution model and that if GW170817 is a representative event, then the merging neutron stars can be considered as the main r-process production sites.

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References

  1. Abbott BP et al (2017) GW170814: a three-detector observation of gravitational waves from a binary black hole coalescence. Phys Rev Lett 119:1101

    Google Scholar 

  2. Asplund M, Grevesse N, Sauval S, Scott P (2009) The chemical composition of the sun. ARA&A 47:481

    CAS  Article  Google Scholar 

  3. Cescutti G et al (2015) The role of neutron star mergers in the chemical evolution of the Galactic halo. A&A 577:139

    Article  Google Scholar 

  4. Chiappini C, Matteucci F, Gratton R (1997) The chemical evolution of the galaxy: the two-infall model. ApJ 477:765

    CAS  Article  Google Scholar 

  5. Coté B et al (2018) The origin of r-process elements in the milky way. ApJ 855:99

    Article  Google Scholar 

  6. Cowan JJ, Thielemann F-K, Truran JW (1991) The R-process and nucleochronology. PhR 208:267

    CAS  Google Scholar 

  7. Evans PA et al (2017) Swift and NuSTAR observations of GW170817: detection of a blue kilonova. Science 358(6370):1565

    CAS  Article  Google Scholar 

  8. Frebel A (2010) Stellar archaeology: exploring the Universe with metal-poor stars. Astronom Nachrichten 331(5):474

    CAS  Article  Google Scholar 

  9. François et al (2007) First stars. VIII. Enrichment of the neutron-capture elements in the early Galaxy. A&A 476:935

    Article  Google Scholar 

  10. Freiburghaus C, Rosswog S, Thielemann (1999) R-process in neutron star mergers. ApJ 525:L121

    CAS  Article  Google Scholar 

  11. Kalogera V, Henninger M, Ivanova N, King AR (2004) An observational diagnostic for ultraluminous x-ray sources. ApJ 601:L41

    Article  Google Scholar 

  12. Komiya Y, Yamada S, Suda T, Fujimoto MY (2014) The new model of chemical evolution of r-process elements based on the hierarchical galaxy formation. I. Ba and Eu. ApJ 783:132

    Article  Google Scholar 

  13. Korobkin O, Rosswog S, Arcones A, Winteler (2012) On the astrophysical robustness of the neutron star merger r-process. MNRAS 426:1940

    CAS  Article  Google Scholar 

  14. Lattimer JM, Schramm DN, Grossman L (1977) Supernovae, grains and the formation of the solar system. Nature 269:116

    CAS  Article  Google Scholar 

  15. Matteucci F, Romano D, Arcones A, Korobkin O, Rosswog S (2014) Europium production: neutron star mergers versus core-collapse supernovae. MNRAS 438:2177 (M14)

    CAS  Article  Google Scholar 

  16. Meyer BS (1989) Decompression of initially cold neutron star matter—a mechanism for the r-process? ApJ 343:254

    CAS  Article  Google Scholar 

  17. Mishenina TV et al (2007) Abundances of neutron-capture elements in atmospheres of cool giants. Astron Rep 51(5):382

    CAS  Article  Google Scholar 

  18. Ramya P, Reddy BE, Lambert DL (2012) Chemical compositions of stars in two stellar streams from the Galactic thick disc. MNRAS 425:3188

    Article  Google Scholar 

  19. Reddy BE, Lambert DL, Allende Prieto C (2006) Elemental abundance survey of the Galactic thick disc. MNRAS 367:1329

    CAS  Article  Google Scholar 

  20. Romano D, Karakas AI, Tosi M, Matteucci F (2010) Quantifying the uncertainties of chemical evolution studies. II. Stellar yields. A&A 522:32

    Article  Google Scholar 

  21. Rosswog S et al (1999) Mass ejection in neutron star mergers. A&A 341:499

    Google Scholar 

  22. Rosswog S, Davies MB, Thielemann F-K, Piran T (2000) Merging neutron stars: asymmetric systems. A&A 360:171

    CAS  Google Scholar 

  23. Scalo JM (1986) The stellar initial mass function. FCPh 11:1

    CAS  Google Scholar 

  24. Tanvir NR et al (2017) The emergence of a Lanthanide-rich Kilonova following the merger of two neutron stars. ApJ 848:L27

    Article  Google Scholar 

  25. Thielemann F-K, Isern J, Perego A, von Ballmoos (2018) Nucleosynthesis in supernovae. SSRv 214:62

    Google Scholar 

  26. Troja E et al (2017) The X-ray counterpart to the gravitational-wave event GW170817. Nature 551:71

    Article  Google Scholar 

  27. Vangioni E et al (2015) The impact of star formation and gamma-ray burst rates at high redshift on cosmic chemical evolution and reionization. MNRAS 447:2575

    CAS  Article  Google Scholar 

  28. Vescovi D, Busso M, Palmerini S (2018) On the origin of early solar system radioactivities: problems with the asymptotic giant branch and massive star scenarios. ApJ 863:115

    Article  Google Scholar 

  29. Wanajo S et al (2001) The r-process in neutrino-driven winds from nascent, “Compact” neutron stars of core-collapse supernovae. ApJ 554:578

    Article  Google Scholar 

  30. Winteler C et al (2012) Magnetorotationally driven supernovae as the origin of early galaxy r-process elements? ApJ 750:L22

    Article  Google Scholar 

  31. Woosley SE et al (1994) The r-process and neutrino-heated supernova ejecta. ApJ 433:229

    CAS  Article  Google Scholar 

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Correspondence to Francesca Matteucci.

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This paper is the peer-reviewed version of a contribution selected among those presented at the Conference on Gamma-Ray Astrophysics with the AGILE Satellite held at Accademia Nazionale dei Lincei and Agenzia Spaziale Italiana, Rome, on December 11–13, 2017.

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Matteucci, F., Romano, D., Cescutti, G. et al. Binary neutron stars and production of heavy elements. Rend. Fis. Acc. Lincei 30, 85–88 (2019). https://doi.org/10.1007/s12210-018-0754-z

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Keywords

  • Stellar nucleosynthesis
  • Galaxy evolution