Anisotropic infall in the outskirts of OmegaWINGS galaxy clusters

SALERNO, JUAN MANUEL; MARTÍNEZ, HÉCTOR J; MURIEL, HERNÁN; COENDA, VALERIA; VULCANI, BENEDETTA; POGGIANTI, BIANCA; MORETTI, ALESSIA; GULLIEUSZIK, MARCO; FRITZ, JACOPO; BETTONI, DANIELA

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2020 vol. 493 p. 4950 - 4959

0035-8711

We study the effects of the environment on galaxy quenching in the outskirts of clusters at 0.04< z < 0.08. We use a subsample of 14 WINGS and OmegaWINGS clusters that are linkedto other groups/clusters by filaments and study separately galaxies located in two regions inthe outskirts of these clusters according to whether they are located towards the filaments?directions or not. We also use samples of galaxies in clusters and field as a comparison.Filamentary structures linking galaxy groups/clusters were identified over the Six DegreeField Galaxy Redshift Survey Data Release 3. We find a fraction of passive galaxies in theoutskirts of clusters intermediate between that of the clusters and the field?s. We find evidenceof a more effective quenching in the direction of the filaments. We also analyse the abundanceof post-starburst (PS) galaxies in the outskirts of clusters focusing our study on two extremesets of galaxies according to their phase-space position: backsplash and true infallers. We findthat up to ∼ 70 per cent of PS galaxies in the direction of filaments are likely backsplash,while this number drops to ∼ 40 per cent in the isotropic infall region. The presence of thissmall fraction of galaxies in filaments that are falling into clusters for the first time and havebeen recently quenched, supports a scenario in which a significant number of filament galaxieshave been quenched long time ago.