Positive deconvolution for superimposed extended source and point sources

¹ Groupe Problèmes Inverses, Laboratoire des Signaux et Systèmes ( – Supélec – ), Plateau de Moulon, 91192 Gif-sur-Yvette, France e-mail: giova@lss.supelec.fr
² Laboratoire d'Étude du Rayonnement de la Matière en Astrophysique (), Observatoire de Paris, 61 Avenue de l'Observatoire, 75014 Paris, France e-mail: alain.coulais@obspm.fr

Received: 5 January 2004
Accepted: 2 May 2005

Abstract

The paper deals with the construction of images from visibilities acquired using aperture synthesis instruments: Fourier synthesis, deconvolution, and spectral interpolation/extrapolation. Its intended application is to specific situations in which the imaged object possesses two superimposed components: (i) an extended component together with (ii) a set of point sources. It is also specifically designed to the case of positive maps, and accounts for a known support. Its originality lies within joint estimation of the two components, coherently with data, properties of each component, positivity and possible support. We approach the subject as an inverse problem within a regularization framework: a regularized least-squares criterion is specifically proposed and the estimated maps are defined as its minimizer. We have investigated several options for the numerical minimization and we propose a new efficient algorithm based on augmented Lagrangian. Evaluation is carried out using simulated and real data (from radio interferometry) demonstrating the capability to accurately separate the two components.