We present results of a population synthesis study aimed at examining the
role of spin-kick alignment in producing a correlation between the spin period
of the first-born neutron star and the orbital eccentricity of observed double
neutron star binaries in the Galactic disk. We find spin-kick alignment to be
compatible with the observed correlation, but not to alleviate the requirements
for low kick velocities suggested in previous population synthesis studies. Our
results furthermore suggest low- and high-eccentricity systems may form through
two distinct formation channels distinguished by the presence or absence of a
stable mass transfer phase before the formation of the second neutron star. The
presence of highly eccentric systems in the observed sample of double neutron
stars may furthermore support the notion that neutron stars accrete matter when
moving through the envelope of a giant companion.Comment: To appear in the proceedings of "40 Years of Pulsars: Millisecond
Pulsars, Magnetars, and More", August 12-17, 2007, McGill University,
Montreal, Canad
