Matrix Filters for the Detection of Extragalactic Point Sources in Cosmic Microwave Background Images

TL;DR

This paper introduces matrix filters, a new linear filtering method that enhances detection of extragalactic point sources in Cosmic Microwave Background images by leveraging cross-channel correlations, outperforming traditional methods.

Contribution

The paper presents a novel matrix filter technique that maximizes signal-to-interference ratio by utilizing cross-channel correlations, improving detection performance over standard matched filters.

Findings

Improved signal-to-noise ratio in simulated CMB images.

Higher number of true detections with fewer false alarms.

Outperforms standard matched filters in tested scenarios.

Abstract

In this paper we introduce a new linear filtering technique, the so-called matrix filters, that maximizes the signal-to-interference ratio of compact sources of unknown intensity embedded in a set of images by taking into account the cross-correlations between the different channels. By construction, the new filtering technique outperforms (or at least equals) the standard matched filter applied on individual images. An immediate application is the detection of extragalactic point sources in Cosmic Microwave Background images obtained at different wavelengths. We test the new technique in two simulated cases: a simple two-channel case with ideal correlated color noise and more realistic simulations of the sky as it will be observed by the LFI instrument of the upcoming ESA's Planck mission. In both cases we observe an improvement with respect to the standard matched filter in terms of signal-to-noise interference, number of detections and number of false alarms.