astrophysics - Create heatmap from significance

I am working on my project in astrophysics and I would like to create my heatmap from the significance which is obtained by the gaussian fitting my histogram.

I get this map :

First picture : convolve heatmap at 2' - convolve completeness map at 2'
Second picture : convolve heatmap at 8' - convolve completeness map at 8'
Third picture : first one - second one

I plot the histogram and the gaussian which is fitting it :

And I obtain this values :

Mean value : -0.0138901955853

Variance value : 0.00824390390031

Sigma value : 0.0907959464971

I would like to get something like this :

==> Question :

How I can process in order to get the same significance map (Signal to Noise) ?