Searching for a cosmological preferred axis: Union2 data analysis and comparison with other probes

We review, compare and extend recent studies searching for evidence for a preferred cosmological axis. We start from the Union2 SnIa dataset and use the hemisphere comparison method to search for a preferred axis in the data. We find that the hemisphere of maximum accelerating expansion rate is in the direction (l, b) = (309◦+23 −3 ◦ , 18 ◦+11◦ −10◦) (Ω0m = 0.19) while the hemisphere of minimum acceleration is in the opposite direction (l, b) = (129◦+23