Ghirlanda G, Salafia O S, Paragi Z, Giroletti M, Yang J, Marcote B, Blanchard J, Agudo I, An T, Bernardini M G, Beswick R, Branchesi M, Campana S, Casadio C, Chassande-Mottin E, Colpi M, Covino S, D'Avanzo P, D'Elia V, Frey S, Gawronski M, Ghisellini G, Gurvits L I, Jonker P G, van Langevelde H J, Melandri A, Moldon J, Nava L, Perego A, Perez-Torres M A, Reynolds C, Salvaterra R, Tagliaferri G, Venturi T, Vergani S D, Zhang M
Istituto Nazionale di Astrofisica-Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate, Italy.
Dipartimento di Fisica G. Occhialini, Università di Milano-Bicocca, Piazza della Scienza 3, IT-20126 Milano, Italy.
Science. 2019 Mar 1;363(6430):968-971. doi: 10.1126/science.aau8815. Epub 2019 Feb 21.
The binary neutron star merger event GW170817 was detected through both electromagnetic radiation and gravitational waves. Its afterglow emission may have been produced by either a narrow relativistic jet or an isotropic outflow. High-spatial-resolution measurements of the source size and displacement can discriminate between these scenarios. We present very-long-baseline interferometry observations, performed 207.4 days after the merger by using a global network of 32 radio telescopes. The apparent source size is constrained to be smaller than 2.5 milli-arc seconds at the 90% confidence level. This excludes the isotropic outflow scenario, which would have produced a larger apparent size, indicating that GW170817 produced a structured relativistic jet. Our rate calculations show that at least 10% of neutron star mergers produce such a jet.
双中子星并合事件GW170817是通过电磁辐射和引力波被探测到的。其余晖发射可能是由狭窄的相对论性喷流或各向同性外流产生的。对源尺寸和位移进行高空间分辨率测量能够区分这些情况。我们展示了利用由32台射电望远镜组成的全球网络在并合后207.4天进行的甚长基线干涉测量观测结果。在90%置信水平下，视源尺寸被限制为小于2.5毫角秒。这排除了会产生更大视尺寸的各向同性外流情况，表明GW170817产生了一个结构化的相对论性喷流。我们的发生率计算表明，至少10%的中子星并合会产生这样的喷流。
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