%0 Journal Article
%T The unpolarized macronova associated with the gravitational wave event GW170817
%+ Laboratoire Univers et Particules de Montpellier (LUPM)
%+ Département d'Astrophysique (ex SAP) (DAP)
%A Covino, S.
%A Wiersema, K.
%A Fan, Y.Z.
%A Toma, K.
%A Higgins, A.B.
%A Melandri, A.
%A d'Avanzo, P.
%A Mundell, C.G.
%A Palazzi, E.
%A Tanvir, N.R.
%A Bernardini, M.G.
%A Branchesi, M.
%A Brocato, E.
%A Campana, S.
%A Di Serego Alighieri, S.
%A Götz, D.
%A Fynbo, J.P.U.
%A Gao, W.
%A Gomboc, A.
%A Gompertz, B.
%A Greiner, J.
%A Hjorth, J.
%A Jin, Z.P.
%A Kaper, L.
%A Klose, S.
%A Kobayashi, S.
%A Kopac, D.
%A Kouveliotou, C.
%A Levan, A.J.
%A Mao, J.
%A Malesani, D.
%A Pian, E.
%A Rossi, A.
%A Salvaterra, R.
%A Starling, R.L.C.
%A Steele, I.
%A Tagliaferri, G.
%A Troja, E.
%A van Der Horst, A.J.
%A Wijers, R.A.M.J.
%< avec comité de lecture
%J Nature Astron.
%V 1
%N 11
%P 791-794
%8 2017
%D 2017
%Z 1710.05849
%R 10.1038/s41550-017-0285-z
%K gamma ray: burst
%K polarization: optical
%K upper limit
%K gravitational radiation
%K neutron star
%K nucleosynthesis
%K radioactivity
%K decay
%K geometry
%K galaxy
%K dust
%Z Physics [physics]/Astrophysics [astro-ph]Journal articles
%X The merger of two dense stellar remnants including at least one neutron star is predicted to produce gravitational waves (GWs) and short-duration gamma ray bursts 1$^{,}$2 . In the process, neutron-rich material is ejected from the system and heavy elements are synthesized by r-process nucleosynthesis 1$^{,}$3 . The radioactive decay of these heavy elements produces additional transient radiation termed kilonova or macronova 4$^{–}$10 . We report the detection of linear optical polarization, P = (0.50 ± 0.07)%, 1.46 days after detection of the GWs from GW 170817—a double neutron star merger associated with an optical macronova counterpart and a short gamma ray burst 11$^{–}$14 . The optical emission from a macronova is expected to be characterized by a blue, rapidly decaying component and a red, more slowly evolving component due to material rich in heavy elements—the lanthanides 15 . The polarization measurement was made when the macronova was still in its blue phase, during which there was an important contribution from a lanthanide-free outflow. The low degree of polarization is consistent with intrinsically unpolarized emission scattered by galactic dust, suggesting a symmetric geometry of the emitting region and low inclination of the merger system. Stringent upper limits to the polarization degree from 2.45–9.48 days post-burst are consistent with the lanthanides-rich macronova interpretation.
%G English
%2 https://hal.science/hal-01645876/document
%2 https://hal.science/hal-01645876/file/Covi.pdf
%L hal-01645876
%U https://hal.science/hal-01645876
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