Journal Article

‘Stokes imaging’ of the accretion region in magnetic cataclysmic variables — I. Conception and realization

S. B. Potter, P. J. Hakala and Mark Cropper

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 297, issue 4, pages 1261-1268
Published in print July 1998 | ISSN: 0035-8711
Published online July 1998 | e-ISSN: 1365-2966 | DOI:
‘Stokes imaging’ of the accretion region in magnetic cataclysmic variables — I. Conception and realization

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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.

Keywords: accretion; accretion discs; methods: analytical; techniques: polarimetric; binaries: close; novae; cataclysmic variables; X-rays: stars

Journal Article.  0 words. 

Subjects: Astronomy and Astrophysics

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