Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Binary neutron-star mergers: a review of Einstein's richest laboratory   The merger of binary neutron-stars systems combines in a single process:
extreme gravity, copious emission of gravitational waves, complex microphysics,
and electromagnetic processes that can lead to astrophysical signatures
observable at the largest redshifts. We review here the recent progress in
understanding what could be considered Einstein's richest laboratory,
highlighting in particular the numerous significant advances of the last
decade. Although special attention is paid to the status of models, techniques,
and results for fully general-relativistic dynamical simulations, a review is
also offered on initial data and advanced simulations with approximate
treatments of gravity. Finally, we review the considerable amount of work
carried out on the post-merger phase, including: black-hole formation, torus
accretion onto the merged compact object, connection with gamma-ray burst
engines, ejected material, and its nucleosynthesis.

11
The categories of this paper are: hep-lat
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an