Статья

Spitzer mid-infrared detections of neutron star merger GW170817 suggests synthesis of the heaviest elements

M. M. KasliwalDivision of Physics, Mathematics, and Astronomy, California Institute of Technology , Pasadena, CA 91125, USADaniel KasenDepartment of Astronomy and Department of Physics, University of California, Berkeley , CA 94720-3411, USARyan M. LauDivision of Physics, Mathematics, and Astronomy, California Institute of Technology , Pasadena, CA 91125, USAD. A. PerleyAstrophysics Research Institute, Liverpool John Moores University , IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UKStephan RosswogThe Oskar Klein Centre, Department of Astronomy, Stockholm University , AlbaNova, SE-106 91 Stockholm, SwedenE. O. OfekDepartment of Particle Physics & Astrophysics, Weizmann Institute of Science , Rehovot 7610001, IsraelKenta HotokezakaDepartment of Astrophysical Sciences, Princeton University , 4 Ivy Lane Princeton, NJ 08544, USARanga‐Ram CharyInfrared Processing and Analysis Center , Caltech, Pasadena, CA 91125, USAJ. SollermanThe Oskar Klein Centre, Department of Astronomy, Stockholm University , AlbaNova, SE-106 91 Stockholm, SwedenA. GoobarThe Oskar Klein Centre, Department of Physics, Stockholm University, AlbaNova , SE-106 91 Stockholm, SwedenD. L. KaplanDepartment of Physics, University of Wisconsin , Milwaukee, WI 53201, USA

2019en

ABI

Аннотация

Abstract We report our Spitzer Space Telescope observations and detections of the binary neutron star merger GW170817. At 4.5 μm, GW170817 is detected at 21.9 mag AB at +43 days and 23.9 mag AB at +74 days after merger. At 3.6 μm, GW170817 is not detected to a limit of 23.2 mag AB at +43 days and 23.1 mag AB at +74 days. Our detections constitute the latest and reddest constraints on the kilonova/macronova emission and composition of heavy elements. The 4.5 μm luminosity at this late phase cannot be explained by elements exclusively from the first abundance peak of the r-process. Moreover, the steep decline in the Spitzer band, with a power-law index of 3.4 ± 0.2, can be explained by a few of the heaviest isotopes with half-life around 14 d dominating the luminosity (e.g. 140Ba, 143Pr, 147Nd, 156Eu, 191Os, 223Ra, 225Ra, 233Pa, 234Th) or a model with lower deposition efficiency. This data offers evidence that the heaviest elements in the second and third r-process abundance peak were indeed synthesized. Our conclusion is verified by both analytics and network simulations and robust despite intricacies and uncertainties in the nuclear physics. Future observations with Spitzer and James Webb Space Telescope will further illuminate the relative abundance of the synthesized heavy elements.

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Идентификаторы

DOI: 10.1093/mnrasl/slz007

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