Light element variations in globular clusters via nucleosynthesis in
  black hole accretion discs
  Ancient globular clusters contain multiple stellar populations identified by
variations in light elements (e.g., C, N, O, Na). Although many scenarios have
been suggested to explain this phenomenon, all are faced with challenges when
compared with all the observational evidence. In this Letter, we propose a new
scenario in which light element variations originate from nucleosynthesis in
accretion discs around black holes. Since the black holes form after a few
$Myrs$, the cluster is expected to still be embedded in a gas rich environment.
Through a simplified accretion model, we show that the correct light element
anti-correlations can be produced. Assuming a Kroupa stellar initial mass
function (IMF), each black hole would only have to process
${\approx}300M_{\odot}$ of material in order to explain multiple populations;
over a period of $3Myr$ this corresponds to $ \sim10^{-4} M_{\odot}yr^{-1}$
(similar to the estimated accretion rate for the X-ray binary SS 433).
