Open Access‘Stokes imaging’ of the accretion region in magnetic cataclysmic variables — I. Conception and realization
Author(s) -
Potter S. B.,
Hakala P. J.,
Cropper Mark
Publication year - 1998
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1998.01608.x
Subject(s) - physics , white dwarf , cataclysmic variable star , polarization (electrochemistry) , accretion (finance) , astrophysics , intermediate polar , cyclotron , astronomy , light curve , accretion disc , magnetic field , stars , chemistry , quantum mechanics
Modelling the polarized cyclotron emission from magnetic cataclysmic variables has been a pivotal technique for determining the structure of the accretion zones on the white dwarf. To date, model solutions have been obtained from trial fits to the intensity and polarization data, which have been constructed from emission regions (for example arcs and spots) put in by hand. These models were all inferred indirectly from arguments based on the polarization and X‐ray light curves. We present a more analytical and objective technique using optimization by a genetic algorithm, Tikhonov regularization and Powell's method that robustly models the details of polarized emission. To demonstrate the success of this technique, we show the results of several simulations in which we calculated the intensity and polarization curves from arbitrarily shaped emission regions on the surface of a sphere and then applied our code to these curves to recover the original test data. We also show how adding artificial noise affects the outcome of the optimization technique.