  Context. A large fraction of transneptunian objects are found in binary
pairs, ~30% in the cold classical population between $a_\text{hel}$~39 and ~48
AU. Observationally, these binaries generally have components of similar size
and colour. Previous work has shown that gravitational collapse of a pebble
cloud is an efficient mechanism for producing such systems. Since the discovery
of the bi-lobate nature of Arrokoth there is also interest in gravitational
collapse as a way to form contact binaries.
  Aims. Our aim was to investigate formation of binary systems via
gravitational collapse, considering a wider range of binary masses than
previous studies. We analysed in detail the properties of the bound systems
that are formed and compared them to observations.
  Methods. We performed N-body simulations of gravitational collapse of a
pebble cloud using the REBOUND package, with an integrator designed for
rotating reference frames and robust collision detection. We conducted a deep
search for gravitationally bound particles at the end of the gravitational
collapse phase and tested their stability. For all systems produced, not just
the most massive binaries, we investigated the population characteristics of
their mass and orbital parameters. Gravitational collapse can create binary
systems analogous to Arrokoth and collisions in a collapsing cloud should be
gentle enough to preserve a bi-lobed structure.
  Results. Gravitational collapse is an efficient producer of bound
planetesimal systems. On average ~1.5 bound systems were produced per cloud in
the mass range studied here. As well as the large equal-sized binaries, we
found that gravitational collapse produces massive bodies with small satellites
and low mass binaries with a high mass ratio. Our results disfavour the
collapse of high mass clouds, in line with reported upper mass limits of clouds
formed by the streaming instability.
