Multiple merging in the Abell cluster 1367

Abstract

Abstract. We present a dynamical analysis of the central ∼1.3 square degrees of the cluster of galaxies Abell 1367, based on 273 redshift measurements (of which 119 are news). From the analysis of the 146 confirmed cluster members we derive a significantly non-Gaussian velocity distribution, with a mean location C BI = 6484 ± 81 km s −1 and a scale S BI = 891 ± 58 km s −1 . The cluster appears elongated from the North-West to the South-East with two main density peaks associated with two substructures. The North-West subcluster is probably in the early phase of merging into the South-East substructure (∼0.2 Gyr before core crossing). A dynamical study of the two subclouds points out the existence of a group of star-forming galaxies infalling into the core of the South-East subcloud and suggests that two other groups are infalling into the NW and SE subclusters respectively. These three subgroups contain a higher fraction of star-forming galaxies than the cluster core, as expected during merging events. Abell 1367 appears as a young cluster currently forming at the intersection of two filaments.

Star Formation and Substructure in Galaxy Clusters

“…The number of emission-line galaxies was then counted as a function of angle from this connecting line. Cortese et al (2004), Ferrari et al (2005), and Wegner (2011) argued for enhanced SF between components using visual inspection, confirmed by statistical tests of the difference between the distributions of emission-line and non-emission-line galaxies (such as the two-dimensional Kolmogorov-Smirnovov test).…”

“…To more definitively study where the higher fraction of SF might reside in multi-component clusters, in this section, we investigate the presence of star-forming galaxies in the regions between centers of cluster components, since a number of studies show an enhancement of SF specifically in the regions between two merging subclusters (e.g., Cortese et al 2004;Ferrari et al 2005;Hwang & Lee 2009;Wegner 2011). We seek to determine whether the higher SF we observe in our multi-component clusters in the previous section might be especially concentrated in regions between component centers.…”

“…A number of studies have recently addressed the issue of how cluster mergers disrupt this expected SF distribution by comparing cluster substructure and SF properties. Several clusters show an enhanced presence of emission-line galaxies in clusters with substructure: for example, A1367 (Cortese et al 2004), A3158 (Johnston-Hollitt et al 2008), the "bullet cluster" (Rawle et al 2010), and A2465 (Wegner 2011). In the Group Environment and Evolution Collaboration group catalog, Hou et al (2012) found higher fractions of blue and star-forming galaxies in rich groups with substructure than in those without, but Hou et al (2013) found no correlation between quiescent fraction and group dynamical state.…”

Planckearly results. VIII. The all-sky early Sunyaev-Zeldovich cluster sample

“…In addition, it may suffer from point source contamination. The cluster Abell 1367 at z = 0.02 with D SZ−X = 7.8 arcmin is a young cluster currently forming at the intersection of two filaments (Cortese et al 2004) with complex gas density and temperature structures (Ghizzardi et al 2010). As seen from Fig.…”

AGES Observations of Abell 1367

“…The Abell cluster 1367, due to its proximity (z ∼ 0.0216) and to the fact that it is currently forming at the intersection of two filaments in the Great Wall (Cortese et al 2004), represents an ideal target for HI blind surveys in order to study the properties of HI selected galaxies and environmental effects. For these reasons, Abell1367 is one of the region observed as a part of the Arecibo Galaxy Environment Survey (AGES, Auld et al 2006), one of the new HI blind survey carried out with the ALFA multibeam system.…”