400d survey: expected false detections

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False detections

The false detection rate was derived by simulating "empty" images (those containing only point sources and the diffuse background) and running them through our analysis algorithm. All extended sources found in these runs are false. The results are summarized in the figures below. Flux distribution of
false sources

The smooth lines show the flux distribution of false detection. The long-dashed line is for the randomly distributed sources and the short-dashed lines for sources with angular correlation. The histogram shows the flux distribution of unidentified sources in the 400d sample.

From the simulations we expect on avearge 18.6 false detection if the background point sources are uncorrelated and 27.1 if ther are correlated. This agrees nicely with the presence of 16 unidentified sources in the survey.

The distribution of false detections and unidentified sources in the flux-radius plane is also similar:

The contours here are drawn on the isodensity levels of the distribution. The labels indicate how many false detections are expected outside the contour.