Ringing effects reduction by improved deconvolution algorithmApplication to A370 CFHT image of gravitational arcs

Muriel Roche (1, 2) , Christian Bracco (2) , Claude Aime (2) , Henri Lanteri (2) , Yannick Mellier (3, 4)

1 FRESNEL - Institut FRESNEL
2 LUAN - Laboratoire Universitaire d'Astrophysique de Nice
3 IAP - Institut d'Astrophysique de Paris
4 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique

We develop a self-consistent automatic procedure to restore informations from astronomical observations. It relies on both a new deconvolution algorithm called LBCA (Lower Bound Constraint Algorithm) and the use of the Wiener filter. In order to explore its scientific potential for strong and weak gravitational lensing, we process a CFHT image of the galaxies cluster Abell 370 whichexhibits spectacular strong gravitational lensing effects. A highquality restoration is here of particular interest to map the darkmatter within the cluster. We show that the LBCA turns out specially efficient to reduceringing effects introduced by classical deconvolution algorithms in images with a high background. The method allows us to make a blind detection of the radial arc and to recover morphological properties similar to thoseobserved from HST data. We also show that the Wiener filter is suitable to stop the iterative process before noise amplification, using only the unrestored data.

Mots clés: image processing; Cluster Abell 370; Cosmology; Gravitational lensing; dark matter; data analysis; image processing.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]

Muriel Roche, Christian Bracco, Claude Aime, Henri Lanteri, Yannick Mellier. Ringing effects reduction by improved deconvolution algorithmApplication to A370 CFHT image of gravitational arcs. 2003. ⟨hal-00000432⟩