Radiative cooling functions for primordial molecules
  Cooling of primordial gas plays a crucial role in the birth of the first
structures in our Universe. Due to the low fractional abundance of molecular
species at high redshifts, spontaneous emission rather than collisions
represents the most efficient way to cool the pristine plasma. In the present
work, radiative cooling functions are evaluated for the diatomic species HD,
HD$^+$, HeH$^+$, LiH and LiH$^+$. Cooling functions for the triatomic ions
H$_3^+$ and H$_2$D$^+$ are also considered. Analytic fits as functions of
temperature are provided.
