A full sky, low foreground, high resolution CMB map from WMAP

¹ Laboratoire AstroParticule et Cosmologie (APC), CNRS: UMR 7164, Université Paris Diderot – Paris 7, 10 rue A. Domon et L. Duquet, 75205 Paris Cedex 13, France e-mail: delabrouille@apc.univ-paris7.fr

² Laboratoire de Traitement et Communication de l'Information (LTCI), CNRS: UMR 5141, Télécom ParisTech, 46 rue Barrault, 75634 Paris Cedex, France

³ Laboratoire Paul Painlevé, CNRS: UMR 8524, Université Lille 1, 59655 Villeneuve d'Ascq Cedex, France

⁴ Modélisation Aléatoire de Paris X (MODAL'X), Université Paris Ouest – Nanterre-la-Défense, 200 avenue de la République, 92001 Nanterre Cedex, France
⁵ Laboratoire de Probabilités et Modèles Aléatoires (LPMA), CNRS: UMR 7599, Université Paris Diderot – Paris 7, 175 rue du Chevaleret, 75013 Paris, France

Received: 3 July 2008
Accepted: 18 October 2008

Abstract

Context. The WMAP satellite has made available high quality maps of the sky in five frequency bands ranging from 22 to 94 GHz, with the main scientific objective of studying the anisotropies of the Cosmic Microwave Background (CMB). These maps, however, contain a mixture of emission from various astrophysical origin, superimposed on CMB emission.

Aims. The objective of the present work is to make a high resolution CMB map in which contamination by such galactic and extra-galactic foreground emissions, as well as by instrumental noise, is as low as possible.

Methods. The method used is an implementation of a constrained linear combination of the channels with minimum error variance, and of Wiener filtering, on a frame of spherical wavelets called needlets, allowing localised filtering in both pixel space and harmonic space.

Results. We obtain a low contamination low noise CMB map at the resolution of the WMAP W channel, which can be used for a range of scientific studies. We obtain also a Wiener-filtered version with minimal integrated error.

Conclusions. The resulting CMB maps offer significantly better rejection of galactic foreground than previous CMB maps from WMAP data. They can be considered as the most precise full-sky CMB temperature maps to date.