Hydrogen line emission from various accretion disk models

The hydrogen line emission expected from the disks of cataclysmic variables is investigated using various accretion disk models. The thick, low viscosity, time-dependent models of Mineshige and Wood are considered first. Next, we considered a series of moderate to high viscosity, steady state α-disk models. On top of these disk models it is assumed that there is a hot "chromosphere" which results from the reprocessing of boundary layer radiation. We find that the low viscosity disk models are generally optically thick and the predicted line equivalent widths were much smaller than expected for dwarf novae in quiescence. Increasing the energy input into the chromosphere by a factor of 10 had a relatively small effect on line equivalent widths. The steady state α-disk models with high viscosity (α≈10-100) seem to hold the most promise for producing the observed equivalent widths.