Point source detection and false discovery rate control on CMB maps

We discuss the STEM (Smoothing and Testing Multiple hypotheses) procedure to search for point sources in Cosmic Microwave background maps; in particular, we aim at controlling the so-called False Discovery Rate, which is defined as the expected value of false discoveries among pixels which are labeled as contaminated by point sources. STEM is based on the following four steps: (1) needlet filtering of the observed CMB maps, to improve the signal to noise ratio; (2) selection of candidate peaks, i.e., the local maxima of filtered maps; (3) computation of p-values for local maxima; (4) implementation of the multiple testing procedure, by means of the so-called Benjamini–Hochberg method. These procedures are also implemented on the latest release of Planck CMB maps.