Indirect imaging of the accretion stream in eclipsing polars - I. Method and tests

We present a method to deduce the brightness distribution of the accretion stream in eclipsing polars using photometric eclipse profiles and an indirect imaging technique based on Maximum Entropy. Our method is developed from that of Hakala and includes improvements to the assumed trajectory of the stream and to the numerical algorithm used to extract the information from an eclipse profile. We present tests of the method using synthetic data, and show that the method is able to retrieve details of the stream brightness distribution from an eclipse profile in the presence of moderate noise, provided the phase resolution of the light curve is good. The method can be applied to the eclipse profiles of any polar with a bright accretion stream to identify regions of enhanced emission between the two stars. The method also provides estimates of the radius at which the accretion stream becomes threaded onto the magnetic field of the white dwarf, and of the mass transfer rate through the stream.