Simulation of Accretion Disk Wind Spectra in Cataclysmic Variables with a 3D non-LTE Monte-Carlo Radiation Transfer Code

• Applicant: Professor Dr. Klaus Werner
• Subject Area: Astrophysics and Astronomy
• Term: from 2006 to 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 24942277

Our primary aim is to complete the development of our 3-D Monte Carlo (MC) radiation transfer code to enable the computation of synthetic spectra of winds from cataclysmic variable stars (CVs). The MC code will solve the radiation transfer equation under the constraints of statistical equilibrium (non-LTE) and energy conservation. This code will be the first tool that does not rely on simplifying assumptions on ionisation balance and atomic level populations. The solution of the full non-LTE problem in a MC code appears feasible now after recent pioneering developments achieved by L.B. Lucy (so-called macroatom approach). Our second aim is to improve the outflow models for CV winds. At present the mass-loss rates obtained from hydrodynamical models are 1-2 orders of magnitude below those expected from observations. We think that this inconsistency roots in the highly simplified treatment of atomic physics, radiation field, and ionisation stratification. Our MC approach will for the first time give precise information on the physical conditions in the wind plasma. Our third aim is the comparison of synthetic spectra to observations in order to estimate the influence of various model parameters. The MC code will complete our program package that will allow the description of all spectral components of the entire CV system (white dwarf, accretion disk, disk wind).

• DFG Programme: Research Grants
• Participating Person: Professor Dr. Achim Feldmeier