Spectroscopic identification of r-process nucleosynthesis in a double neutron star merger

E. Pian; P. d'Avanzo; S. Benetti; M. Branchesi; E. Brocato; S. Campana; E. Cappellaro; S. Covino; V. d'Elia; J.P.U. Fynbo; F. Getman; G. Ghirlanda; G. Ghisellini; A. Grado; G. Greco; J. Hjorth; C. Kouveliotou; A. Levan; L. Limatola; D. Malesani; P.A. Mazzali; A. Melandri; P. Møller; L. Nicastro; E. Palazzi; S. Piranomonte; A. Rossi; O.S. Salafia; J. Selsing; G. Stratta; M. Tanaka; N.R. Tanvir; L. Tomasella; D. Watson; S. Yang; L. Amati; L.A. Antonelli; S. Ascenzi; M.G. Bernardini; M. Boër; F. Bufano; A. Bulgarelli; M. Capaccioli; P.G. Casella; A.J. Castro-Tirado; E. Chassande-Mottin; R. Ciolfi; C.M. Copperwheat; M. Dadina; G. de Cesare; A. Di Paola; Y.Z. Fan; B. Gendre; G. Giuffrida; A. Giunta; L.K. Hunt; G. Israel; Z.-P. Jin; M. Kasliwal; S. Klose; M. Lisi; F. Longo; E. Maiorano; M. Mapelli; N. Masetti; L. Nava; B. Patricelli; D. Perley; A. Pescalli; T. Piran; A. Possenti; L. Pulone; M. Razzano; R. Salvaterra; P. Schipani; M. Spera; A. Stamerra; L. Stella; G. Tagliaferri; V. Testa; E. Troja; M. Turatto; S.D. Vergani; D. Vergani

doi:10.1038/nature24298

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Spectroscopic identification of r-process nucleosynthesis in a double neutron star merger

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Spectroscopic identification of r-process nucleosynthesis in a double neutron star merger

E. Pian, P. d'Avanzo, S. Benetti, M. Branchesi, E. Brocato, S. Campana, E. Cappellaro, S. Covino, V. d'Elia, J.P.U. Fynbo, …

Nature, Vol.551, pp.67-70

2017

DOI: https://doi.org/10.1038/nature24298

Abstract

gamma ray: burst

mass: solar

n: capture

spectral

gravitational radiation

nucleosynthesis

neutron star

observatory

ultraviolet

platinum

velocity

optical

opacity

galaxy

gold

absorption

The merger of two neutron stars is predicted to give rise to three major detectable phenomena: a short burst of gamma-rays, a gravitational wave signal, and a transient optical/near-infrared source powered by the synthesis of large amounts of very heavy elements via rapid neutron capture (the r-process). Such transients, named "macronovae" or "kilonovae", are believed to be centres of production of rare elements such as gold and platinum. The most compelling evidence so far for a kilonova was a very faint near-infrared rebrightening in the afterglow of a short gamma-ray burst at z = 0.356, although findings indicating bluer events have been reported. Here we report the spectral identification and describe the physical properties of a bright kilonova associated with the gravitational wave source GW 170817 and gamma-ray burst GRB 170817A associated with a galaxy at a distance of 40 Mpc from Earth. Using a series of spectra from ground-based observatories covering the wavelength range from the ultraviolet to the near-infrared, we find that the kilonova is characterized by rapidly expanding ejecta with spectral features similar to those predicted by current models. The ejecta is optically thick early on, with a velocity of about 0.2 times light speed, and reaches a radius of about 50 astronomical units in only 1.5 days. As the ejecta expands, broad absorption-like lines appear on the spectral continuum indicating atomic species produced by nucleosynthesis that occurs in the post-merger fast-moving dynamical ejecta and in two slower (0.05 times light speed) wind regions. Comparison with spectral models suggests that the merger ejected 0.03-0.05 solar masses of material, including high-opacity lanthanides.

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Title: Spectroscopic identification of r-process nucleosynthesis in a double neutron star merger
Creators - without role: E. Pian - Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna
P. d'Avanzo
S. Benetti - Osservatorio Astronomico di Padova
M. Branchesi - Gran Sasso Science Institute
E. Brocato - Astronomical Observatory of Rome
S. Campana - Brera Astronomical Observatory
E. Cappellaro - Osservatorio Astronomico di Padova
S. Covino - Brera Astronomical Observatory
V. d'Elia
J.P.U. Fynbo - University of Copenhagen
F. Getman - Astronomical Observatory of Capodimonte
G. Ghirlanda - Brera Astronomical Observatory
G. Ghisellini - Brera Astronomical Observatory
A. Grado - Astronomical Observatory of Capodimonte
G. Greco - University of Urbino
J. Hjorth - University of Copenhagen
C. Kouveliotou - George Washington University
A. Levan - University of Warwick
L. Limatola - Astronomical Observatory of Capodimonte
D. Malesani - University of Copenhagen
P.A. Mazzali - Liverpool John Moores University
A. Melandri - Brera Astronomical Observatory
P. Møller - European Southern Observatory
L. Nicastro - Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna
E. Palazzi - Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna
S. Piranomonte - Astronomical Observatory of Rome
A. Rossi - Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna
O.S. Salafia - Brera Astronomical Observatory
J. Selsing - University of Copenhagen
G. Stratta - University of Urbino
M. Tanaka - National Astronomical Observatory of Japan
N.R. Tanvir - University of Leicester
L. Tomasella - Osservatorio Astronomico di Padova
D. Watson - University of Copenhagen
S. Yang - University of Padua
L. Amati - Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna
L.A. Antonelli - Astronomical Observatory of Rome
S. Ascenzi - Astronomical Observatory of Rome
M.G. Bernardini - Université de Montpellier, Laboratoire Univers et Particules de Montpellier - LUPM
M. Boër - Observatoire de la Côte d’Azur
F. Bufano - Osservatorio Astrofisico di Catania
A. Bulgarelli - Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna
M. Capaccioli - Astronomical Observatory of Capodimonte
P.G. Casella - Astronomical Observatory of Rome
A.J. Castro-Tirado - Instituto de Astrofísica de Andalucía
E. Chassande-Mottin - Commissariat à l'Énergie Atomique et aux Énergies Alternatives
R. Ciolfi - Osservatorio Astronomico di Padova
C.M. Copperwheat - Liverpool John Moores University
M. Dadina - Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna
G. de Cesare - Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna
A. Di Paola - Astronomical Observatory of Rome
Y.Z. Fan - Purple Mountain Observatory
B. Gendre - University of the Virgin Islands
G. Giuffrida - Astronomical Observatory of Rome
A. Giunta - Astronomical Observatory of Rome
L.K. Hunt - Arcetri Astrophysical Observatory
G. Israel - Astronomical Observatory of Rome
Z.-P. Jin - Purple Mountain Observatory
M. Kasliwal - California Institute of Technology
S. Klose - Thüringer Landessternwarte Tautenburg
M. Lisi - Astronomical Observatory of Rome
F. Longo - University of Trieste
E. Maiorano - Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna
M. Mapelli - Universität Innsbruck
N. Masetti - Universidad Andrés Bello
L. Nava - Trieste Astronomical Observatory
B. Patricelli - Scuola Normale Superiore
D. Perley - Liverpool John Moores University
A. Pescalli - University of Insubria
T. Piran - Astronomical Observatory of Rome
A. Possenti - Osservatorio Astronomico di Cagliari
L. Pulone - Astronomical Observatory of Rome
M. Razzano - Scuola Normale Superiore
R. Salvaterra - Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano
P. Schipani - Astronomical Observatory of Capodimonte
M. Spera - Osservatorio Astronomico di Padova
A. Stamerra - Scuola Normale Superiore
L. Stella - Astronomical Observatory of Rome
G. Tagliaferri - Brera Astronomical Observatory
V. Testa - Astronomical Observatory of Rome
E. Troja - Goddard Space Flight Center
M. Turatto - Osservatorio Astronomico di Padova
S.D. Vergani - Université Paris Sciences et Lettres
D. Vergani - Galaxies, Etoiles, Physique et Instrumentation
Publication Details: Nature, Vol.551, pp.67-70
Identifiers: 9938140109311
Academic Unit: Laboratoire Univers et Particules de Montpellier - LUPM
Language: English
Resource Type: Journal article
Local Fields: hal-01645878