The merger locations of binary neutron stars (BNSs) encode their galactic
kinematics and provide insights into their connection to short gamma-ray bursts
(SGRBs). In this work, we use the sample of Galactic BNSs with measured proper
motions to investigate their kinematics and predict their merger locations.
Using a synthetic image of the Milky Way and its Galactic potential we analyse
the BNS mergers as seen from an extragalactic viewpoint and compare them to the
location of SGRBs on and around their host galaxies. We find that the
Galactocentric transverse velocities of the BNSs are similar in magnitude and
direction to those of their Local Standards of Rest, which implies that the
present-day systemic velocities are not isotropically oriented and the peculiar
velocities might be as low as those of BNS progenitors. Both systemic and
peculiar velocities fit a lognormal distribution, with the peculiar velocities
being as low as βΌ22β157 km sβ1. We also find that the observed BNS
sample is not representative of the whole Galactic population, but rather of
systems born around the Sun's location with small peculiar velocities. When
comparing the predicted BNS merger locations to SGRBs, we find that they cover
the same range of projected offsets, host-normalized offsets, and fractional
light. Therefore, the spread in SGRB locations can be reproduced by mergers of
BNSs born in the Galactic disk with small peculiar velocities, although the
median offset match is likely a coincidence due to the biased BNS sample.Comment: 13 pages, 7 figures, accepted for publication in MNRA