Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Supernova Kicks and Misaligned Be Star Binaries   Be stars are rapidly spinning B stars surrounded by an outflowing disc of gas
in Keplerian rotation. Be star/X-ray binary systems contain a Be star and a
neutron star. They are found to have non-zero eccentricities and there is
evidence that some systems have a misalignment between the spin axis of the
star and the spin axis of the binary orbit. The eccentricities in these systems
are thought to be caused by a kick to the neutron star during the supernova
that formed it. Such kicks would also give rise to misalignments. In this paper
we investigate the extent to which the same kick distribution can give rise to
both the observed eccentricity distribution and the observed misalignments. We
find that a Maxwellian distribution of velocity kicks with a low velocity
dispersion, $\sigma_k \approx 15\rm km s^{-1}$, is consistent with the observed
eccentricity distribution but is hard to reconcile with the observed
misalignments, typically $i \ge 25^\circ$. Alternatively a higher velocity kick
distribution, $\sigma_k = 265 \rm km s^{-1}$, is consistent with the observed
misalignments but not with the observed eccentricities, unless post-supernova
circularisation of the binary orbits has taken place. We discuss briefly how
this might be achieved.

23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
16
The categories of this paper are: stat