Two modified ILC methods to detect point sources in Cosmic Microwave Background maps

TL;DR

This paper introduces two modified ILC methods for detecting point sources in Cosmic Microwave Background maps, leveraging small sky area approximation and requiring no prior knowledge of foreground spectra, thus enhancing robustness and ease of use.

Contribution

The paper presents novel modifications to the ILC method that improve point source detection in CMB maps without needing prior spectral information.

Findings

Methods perform well in simulated ALMA-like scenarios

Approach is robust against spectral uncertainties

Simplifies component separation process

Abstract

We propose two detection techniques that take advantage of a small sky area approximation and are based on modifications of the "internal linear combination" (ILC) method, an approach widely used in Cosmology for the separation of the various components that contribute to the microwave background. The main advantage of the proposed approach, especially in handling multi-frequency maps of the same region, is that it does not require the "a priori" knowledge of the spatial power-spectrum of either the CMB and/or the Galactic foreground. Hence, it is more robust, easier and more intuitive to use. The performance of the proposed algorithms is tested with numerical experiments that mimic the physical scenario expected for high Galactic latitude observations with the Atacama Large Millimeter/submillimeter Array (ALMA).