The Supersonic Project: To cool or not to cool Supersonically Induced
  Gas Objects (SIGOs)?
  Supersonically Induced Gas Objects (SIGOs) primarily form in the early
Universe, outside of dark matter halos due to the presence of a relative stream
velocity between baryons and dark matter. These structures may be the
progenitors of globular clusters. Since SIGOs are made out of pristine gas, we
investigate the effect of atomic cooling on their properties. We run a suite of
simulations by using the moving-mesh code {\sc arepo}, with and without
baryon-dark matter relative velocity and with and without the effects of atomic
cooling. We show that SIGO's density, temperature, and prolateness are
determined by gravitational interactions rather than cooling. The cold gas
fraction in SIGOs is much higher than that of dark matter halos. Specifically,
we show that the SIGO's characteristic low temperature and extreme high gas
density forges a nurturing ground for the earliest star formation sites.
