Calculations of radiation forces in AGN
There is a famous characteristic luminosity in astrophysics known as the Eddington limit, which is the luminosity
that would give rise to a radiation force equal to the force of gravity, allowing gas to levitate at this limit and
get pushed outward above it. The Eddington limit applies to radiation pressure acting on free electrons.
If only hydrogen is fully ionized, then there will typically be an enormous opacity due to ions heavier than hydrogen.
In this project, led by PhD student Randall Dannen, we calculated the radiation force due to this 'line opacity'.
We find that radiation forces can surpass gravity in sources emitting far below the Eddington limit, so that radiation driven
outflows are expected to be commonplace in AGN.