TY - JOUR
T1 - AT 2017gfo
T2 - An Anisotropic and Three-component Kilonova Counterpart of GW170817
AU - Perego, Albino
AU - Radice, David
AU - Bernuzzi, Sebastiano
N1 - Publisher Copyright:
© 2017. The American Astronomical Society. All rights reserved.
PY - 2017/12/1
Y1 - 2017/12/1
N2 - The detection of a kilo/macronova electromagnetic counterpart (AT 2017gfo) of the first gravitational-wave signal compatible with the merger of two neutron stars (GW170817) has confirmed the occurrence of r-process nucleosynthesis in this kind of event. The blue and red components of AT 2017gfo have been interpreted as the signature of multi-component ejecta in the merger dynamics. However, the explanation of AT 2017gfo in terms of the properties of the ejecta and of the ejection mechanisms is still incomplete. In this work, we analyze AT 2017gfo with a new semi-analytic model of kilo/macronova inferred from general-relativistic simulations of the merger and long-term numerical models of the merger aftermath. The model accounts for the anisotropic emission from the three known mass ejecta components: dynamic, winds, and secular outflows from the disk. The early multi-band light curves of AT 2017gfo can only be explained by the presence of a relatively low-opacity component of the ejecta at high latitudes. This points to the key role of weak interactions in setting the ejecta properties and determining the nucleosynthetic yields. Our model also constrains the total ejected mass associated to AT 2017gfo to be between 0.042 and 0.077 M⊙, the observation angle of the source to be between π/12 and 7π/36, and the mass of the disk to be ≳0.08 M⊙.
AB - The detection of a kilo/macronova electromagnetic counterpart (AT 2017gfo) of the first gravitational-wave signal compatible with the merger of two neutron stars (GW170817) has confirmed the occurrence of r-process nucleosynthesis in this kind of event. The blue and red components of AT 2017gfo have been interpreted as the signature of multi-component ejecta in the merger dynamics. However, the explanation of AT 2017gfo in terms of the properties of the ejecta and of the ejection mechanisms is still incomplete. In this work, we analyze AT 2017gfo with a new semi-analytic model of kilo/macronova inferred from general-relativistic simulations of the merger and long-term numerical models of the merger aftermath. The model accounts for the anisotropic emission from the three known mass ejecta components: dynamic, winds, and secular outflows from the disk. The early multi-band light curves of AT 2017gfo can only be explained by the presence of a relatively low-opacity component of the ejecta at high latitudes. This points to the key role of weak interactions in setting the ejecta properties and determining the nucleosynthetic yields. Our model also constrains the total ejected mass associated to AT 2017gfo to be between 0.042 and 0.077 M⊙, the observation angle of the source to be between π/12 and 7π/36, and the mass of the disk to be ≳0.08 M⊙.
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U2 - 10.3847/2041-8213/aa9ab9
DO - 10.3847/2041-8213/aa9ab9
M3 - Article
AN - SCOPUS:85037708726
SN - 2041-8205
VL - 850
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 2
M1 - L37
ER -