Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Separated before birth: pulsars B2020+28 and B2021+51 as the remnants of
  runaway stars   Astrometric data on the pulsars B2020+28 and B2021+51 suggest that they
originated within several parsecs of each other in the direction of the Cyg OB2
association. It was proposed that the pulsars share their origin in a common
massive binary and were separated at the birth of the second pulsar following
the asymmetric supernova explosion. We consider a different scenario for the
origin of the pulsar pair based on a possibility that the pulsars were
separated before their birth and that they are the remnants of runaway stars
ejected (with velocities similar to those of the pulsars) from the core of Cyg
OB2 due to strong three- or four-body dynamical encounters. Our scenario does
not require any asymmetry in supernova explosions.

22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio