William Lucas


In situ formation of multiple stellar discs around supermassive black holes

Ian Bonnell, Ken Rice


Observations of the innermost parsec around Sagittarius A* have revealed the existence of two misaligned discs or possibly streamers of O and W-R stars orbiting Sgr A* at radii between about 0.05 and 0.5 pc. This would seem to indicate that two separate star-forming events have taken place around the black hole, yet the stars appear to be coeval which points instead to a single event – something of a problem. Here we use smoothed particle hydrodynamics with a radiative transfer approximation to demonstrate the infall of a prolate ellipsoidal cloud towards a black hole of 4×106 solar masses. The cloud’s geometry provides sufficient spread in angular momentum to create multiple orbiting structures upon tidal shearing.