On the number of young stellar discs in the Galactic Centre
  Observations of the Galactic Centre show evidence of disc-like structures of
very young stars orbiting the central super-massive black hole within a
distance of a few 0.1 pc. While it is widely accepted that about half of the
stars form a relatively flat disc rotating clockwise on the sky, there is a
substantial ongoing debate on whether there is a second, counter-clockwise disc
of stars.
  By means of N-body simulations using our bhint code, we show that two highly
inclined stellar discs with the observed properties cannot be recognised as two
flat circular discs after 5 Myr of mutual interaction. Instead, our
calculations predict a significant warping of the two discs, which we show to
be apparent among the structures observed in the Galactic Centre. While the
high eccentricities of the observed counter-clockwise orbits suggest an
eccentric origin of this system, we show the eccentricity distribution in the
inner part of the more massive clockwise disc to be perfectly consistent with
an initially circular disc in which stellar eccentricities increase due to both
non-resonant and resonant relaxation.
  We conclude that the relevant question to ask is therefore not whether there
are two discs of young stars, but whether there were two such discs to begin
with.
