Foreground component separation with generalised ILC

TL;DR

This paper extends the ILC method to separate multiple correlated astrophysical emissions in millimetre data, demonstrating effective reconstruction of foregrounds in simulated Planck observations.

Contribution

It introduces a multidimensional ILC filter for complex component separation, applicable to multiple correlated emissions, and tests its performance on simulated data.

Findings

Successfully reconstructs low-noise foreground emission estimates

Achieves vanishing CMB and SZ contamination in simulations

Demonstrates effectiveness of generalized ILC on needlet frames

Abstract

The 'Internal Linear Combination' (ILC) component separation method has been extensively used to extract a single component, the CMB, from the WMAP multifrequency data. We generalise the ILC approach for separating other millimetre astrophysical emissions. We construct in particular a multidimensional ILC filter, which can be used, for instance, to estimate the diffuse emission of a complex component originating from multiple correlated emissions, such as the total emission of the Galactic interstellar medium. The performance of such generalised ILC methods, implemented on a needlet frame, is tested on simulations of Planck mission observations, for which we successfully reconstruct a low noise estimate of emission from astrophysical foregrounds with vanishing CMB and SZ contamination.