Coughlan, Colm

Imaging VLBI polarimetry data from Active Galactic Nuclei using the Maximum Entropy Method.

Author list: Colm Coughlan, Denise Gabuzda

Mapping the relativistic jets emanating from AGN requires the use of a deconvolution algorithm to account for the effects of missing visibilities and thermal noise. The CLEAN algorithm is the most commonly used algorithm in VLBI imaging today and is suitable for imaging polarised data. The Maximum Entropy Method (MEM) is presented as an alternative with some advantages over the CLEAN algorithm, including better spatial resolution and a more rigorous and unbiased approach to deconvolution. We have developed a MEM code suitable for deconvolving VLBI polarimetry data. Monte Carlo results demonstrating the performance of CLEAN and the MEM code on a variety of source types are presented. Real polarimetry (VLBA) data taken at multiple wavelengths are also deconvolved using MEM and the resulting polarisation and Faraday rotation maps presented and discussed.