The emergence of a lanthanide-rich kilonova following the merger of two neutron stars
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We report the discovery and monitoring of the near-infrared counterpart (AT2017gfo) of a binary neutron-star merger event detected as a gravitational wave source by Advanced Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo (GW170817) and as a short gamma-ray burst by Fermi Gamma-ray Burst Monitor (GBM) and Integral SPI-ACS (GRB 170817A). The evolution of the transient light is consistent with predictions for the behavior of a “kilonova/macronova” powered by the radioactive decay of massive neutron-rich nuclides created via r-process nucleosynthesis in the neutron-star ejecta. In particular, evidence for this scenario is found from broad features seen in Hubble Space Telescope infrared spectroscopy, similar to those predicted for lanthanide-dominated ejecta, and the much slower evolution in the near-infrared Ks-band compared to the optical. This indicates that the late-time light is dominated by high-opacity lanthanide-rich ejecta, suggesting nucleosynthesis to the third r-process peak (atomic masses A ≈ 195). This discovery confirms that neutron-star mergers produce kilo-/macronovae and that they are at least a major—if not the dominant—site of rapid neutron capture nucleosynthesis in the universe.
Tanvir , N R , Levan , A J , González-Fernández , C , Korobkin , O , Mandel , I , Rosswog , S , Hjorth , J , D’Avanzo , P , Fruchter , A S , Fryer , C L , Kangas , T , Milvang-Jensen , B , Rosetti , S , Steeghs , D , Wollaeger , R T , Cano , Z , Copperwheat , C M , Covino , S , D’Elia , V , Postigo , A D U , Evans , P A , Even , W P , Fairhurst , S , Figuera Jaimes , R , Fontes , C J , Fujii , Y I , Fynbo , J P U , Gompertz , B P , Greiner , J , Hodosan , G , Irwin , M J , Jakobsson , P , Jørgensen , U G , Kann , D A , Lyman , J D , Malesani , D , McMahon , R G , Melandri , A , O’Brien , P T , Osborne , J P , Palazzi , E , Perley , D A , Pian , E , Piranomonte , S , Rabus , M , Rol , E , Rowlinson , A , Schulze , S , Sutton , P , Thöne , C C , Ulaczyk , K , Watson , D , Wiersema , K & Wijers , R A M J 2017 , ' The emergence of a lanthanide-rich kilonova following the merger of two neutron stars ' Astrophysical Journal Letters , vol 848 , no. 2 , L27 . DOI: 10.3847/2041-8213/aa90b6
Astrophysical Journal Letters
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