Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Compact radio emission indicates a structured jet was produced by a
  binary neutron star merger   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, using a
global network of 32 radio telescopes. The apparent source size is constrained
to be smaller than 2.5 milliarcseconds 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.

37
The categories of this paper are: supr-con
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom