Modelling the spectral signatures of accretion disk winds in cataclysmic variables Available to Purchase

Powerful bipolar outflows are known to be present in many disk-accreting astrophysical systems. These outflows can have significant effects on the observed spectra since they may absorb and/or scatter photons emitted by the disk (or any other source of radiation in the system). Here, we present a new hybrid Monte Carlo/Sobolev radiative transfer code which is designed to allow these effects to be modelled quantitatively. Following previous work, we concentrate on the winds from cataclysmic variable stars and adopt a kinematic model in which the outflow is described as a biconical, rotating wind emerging from the surface of the accretion disk. The ionization structure in this disk wind is calculated in an initial run of the code, using an on-the-spot approximation. The radiative transfer of photons through the wind is carried out in the Sobolev approximation, accounting properly for multiple scattering events. The main new feature of our method is that it permits arbitrary sections of the emergent spectrum to be synthesized once the geometric, kinematic and ionization properties of the outflow have been established. We present preliminary results of the application of our new method to the modeling of the EUVE spectrum of the dwarf nova U Gem in outburst.