Dear All, I have a question regarding the understanding of anisotropy of cosmic rays and how to understand them better. To determine the anisotropy I have seen a lot of papers where they use maps that have a Relative Intensity map and a Statistical significance map of the sky. I understand the relative intensity map, but I don't understand why the statistical significance maps are used, could some one explain this to me? Thanks, caart
Sure, here is a paper that I have been recently reading. http://arxiv.org/abs/1105.2326 It's figure 3 at page 15. At section 3.2, they are explained but I don't really understand it yet, they say that they use the Li and Ma paper: http://articles.adsabs.harvard.edu/...pJ...272..317L&defaultprint=YES&filetype=.pdf
I'm actually not certain. At first glance I would think that the significance level depends on the intensity of the radiation and the observation time, with a higher significance corresponding to a higher chance that the signal is real and not a background fluctuation, but I'm not sure why the significance level goes into the negative.