Speaker
Description
Recent catalogue of the Faraday rotation measures (RM) of extragalactic sources, together with the synchrotron polarisation data from WMAP and Planck, provide us with a wealth of information on the magnetic fields of the Galaxy. We combine several phenomenological components of the GMF –- the spiral arms, the toroidal halo, the X-shaped field, and the field of the Local Bubble –- to construct a model of the regular GMF outside the thin disc. We use the binned chi2 approach to fit the parameters of the model to the data. To have control over the relative contributions of the RM and polarisation data to the fit, we pay special attention to the estimation of errors in data bins. To this end, we developed a systematic method that is uniformly applicable to different data sets and takes into account individual measurement errors, the variance in the bin, and fluctuations in the data at angular scales larger than the bin size. We found that the four components listed above are sufficient to fit both the RM and polarisation data over the whole sky with only a small fraction masked out. Important improvements of our model compared to previous approaches are the account for the contribution of the Local Bubble and inclusion of the Fan region into the fit.
