Cyclotron luminosity of narrow offset radiative accretion shocks onto magnetic white dwarfs

Abstract EN

Optical Quasi-periodic oscillations (QPOs) are observed in some Am Her(culls) objects as broadly distributed power excesses over the frequency rang 0.4-0.8 Hz (Middle ditch 1982).

Middle ditch suggested that QPOs are due to an instability of radiative shock waves discovered by Langer, Chanmugam, and Sh aviv (LCS 1981) during time-dependent calculations of acc rection flows onto magnetic white dwarfs.

If this conjecture is correct, then the QPSs can be used as probes of the local conditions of the radiating plasmas and serve to place constrains on several fundamental properties of the Am Her systems (e.g., see Wood, Imamura, and Wolff 1993).

The QPOs are observed in the optical, which is thought to be due to cyclotron emission from the radiating strongly magnetic shoaled plasma.

In most calculations of time-dependent radiative shocks, only Bremsstrahlung is properly treated.

This work together with the calculations of the cyclotron spectra, light curves and luminosities is used to explain the important issue of the nature of the QPO s of the Am Her systems.