The Primordial Binary Population in OB associations

T. Kouwenhoven, A. Brown, L. Kaper, and S. Portegies Zwart

The Primordial Binary Population (PBP) is the population
of binaries (and multiples) which is present after star
formation, just after the gas has been removed. Knowledge
about the PBB allows us to discriminate between different
star forming theories, and provides information about the
formation and evolution of binary systems and star clusters.
We study the PBP in OB associations because of their low
density and young age, so that the binary population is as
close to primordial as possible. We present our adaptive
optics surveys for binarity in the nearby OB association
Sco OB2, which, combined with literature data, constitute
a census on binarity in Sco OB2. This dataset is hampered
by selection effects, which will be studied in detail.
Simulated Observations of Simulations (SOS) will be used
to correct for selection effects, as well as for the
changes in the binary population due to stellar and
dynamical evolution. This will allow us to find the
go back in time to find the Primordial Binary Population.